Have not tested but this patch is incomplete as generate.css has not been ran.
If I run php build/generatecss.php today, I get:

diff --git a/administrator/templates/isis/css/template-rtl.css b/administrator/templates/isis/css/template-rtl.css
index 99a336c..bc30e25 100644
--- a/administrator/templates/isis/css/template-rtl.css
+++ b/administrator/templates/isis/css/template-rtl.css
@@ -8171,8 +8171,8 @@
        padding: 5px 0;
    }
-}
-.modal-body {
-   -webkit-overflow-scrolling: touch;
-   overflow-y: auto !important;
+   .modal-body {
+       -webkit-overflow-scrolling: touch;
+       overflow-y: auto !important;
+   }
 }
 .pull-right {
diff --git a/administrator/templates/isis/css/template.css b/administrator/templates/isis/css/template.css
index ba425fb..bad66c4 100644
--- a/administrator/templates/isis/css/template.css
+++ b/administrator/templates/isis/css/template.css
@@ -2791,5 +2791,5 @@
 }
 .alert h4 {
-  margin: 0 0 .5em;
+   margin: 0 0 .5em;
 }
 .alert .close {
@@ -8171,7 +8171,7 @@
        padding: 5px 0;
    }
-}
-.modal-body {
-   -webkit-overflow-scrolling: touch;
-   overflow-y: auto !important;
+   .modal-body {
+       -webkit-overflow-scrolling: touch;
+       overflow-y: auto !important;
+   }
 }
diff --git a/administrator/templates/isis/less/template.less b/administrator/templates/isis/less/template.less
index 0b1a3d4..c5166af 100644
--- a/administrator/templates/isis/less/template.less
+++ b/administrator/templates/isis/less/template.less
@@ -1324,9 +1324,9 @@
        padding: 5px 0;
    }
-}

-/* Fix iOS scrolling inside bootstrap modals (using iframe) */
-.modal-body {
-   -webkit-overflow-scrolling: touch;
-   overflow-y: auto !important;
+   /* Fix iOS scrolling inside bootstrap modals (using iframe) */
+   .modal-body {
+       -webkit-overflow-scrolling: touch;
+       overflow-y: auto !important;
+   }
 }
diff --git a/templates/protostar/css/template.css b/templates/protostar/css/template.css
index cbc9db4..ff08400 100644
--- a/templates/protostar/css/template.css
+++ b/templates/protostar/css/template.css
@@ -2806,5 +2806,5 @@
 }
 .alert h4 {
-  margin: 0 0 .5em;
+   margin: 0 0 .5em;
 }
 .alert .close {

sorry, didn't knew that. was my first submit to the joomla project.

I made the same comment in #9586

brian, i saw your comment and so i decided to make this pull request. maybe it was a wrong way?

@ucfnet002 @infograf768 see ucfnet002#1

@wojsmol i think you made the patch in wrong branch (ucfnet002:staging) when it should be the ucfnet002:patch-1 branch

@aaleksanyants thank you - fixed

I have tested this item unsuccessfully on 92df354

Works fine on desktop and tablet but not on mobile XS viewport.

The comment held in the less file is as below, I was to busy to amend and test a correct solution.

Fix iOS scrolling inside bootstrap modals (using iframe) */

The testing of this PR would also need to take this into consideration. Was to busy to update the previous PR, and to investigate the reason for the original change.

Possible changes to the code will need to be :

/* ----------- iPhone 4 and 4S ----------- */

/* Portrait and Landscape */
@media only screen
and (min-device-width: 320px)
and (max-device-width: 480px)
and (-webkit-min-device-pixel-ratio: 2) {

}

/* Portrait */
@media only screen
and (min-device-width: 320px)
and (max-device-width: 480px)
and (-webkit-min-device-pixel-ratio: 2)
and (orientation: portrait) {
}

/* Landscape */
@media only screen
and (min-device-width: 320px)
and (max-device-width: 480px)
and (-webkit-min-device-pixel-ratio: 2)
and (orientation: landscape) {

}

/* ----------- iPhone 5 and 5S ----------- */

/* Portrait and Landscape */
@media only screen
and (min-device-width: 320px)
and (max-device-width: 568px)
and (-webkit-min-device-pixel-ratio: 2) {

}

/* Portrait */
@media only screen
and (min-device-width: 320px)
and (max-device-width: 568px)
and (-webkit-min-device-pixel-ratio: 2)
and (orientation: portrait) {
}

/* Landscape */
@media only screen
and (min-device-width: 320px)
and (max-device-width: 568px)
and (-webkit-min-device-pixel-ratio: 2)
and (orientation: landscape) {

}

/* ----------- iPhone 6 ----------- */

/* Portrait and Landscape */
@media only screen
and (min-device-width: 375px)
and (max-device-width: 667px)
and (-webkit-min-device-pixel-ratio: 2) {

}

/* Portrait */
@media only screen
and (min-device-width: 375px)
and (max-device-width: 667px)
and (-webkit-min-device-pixel-ratio: 2)
and (orientation: portrait) {

}

/* Landscape */
@media only screen
and (min-device-width: 375px)
and (max-device-width: 667px)
and (-webkit-min-device-pixel-ratio: 2)
and (orientation: landscape) {

}

/* ----------- iPhone 6+ ----------- */

/* Portrait and Landscape */
@media only screen
and (min-device-width: 414px)
and (max-device-width: 736px)
and (-webkit-min-device-pixel-ratio: 3) {

}

/* Portrait */
@media only screen
and (min-device-width: 414px)
and (max-device-width: 736px)
and (-webkit-min-device-pixel-ratio: 3)
and (orientation: portrait) {

}

/* Landscape */
@media only screen
and (min-device-width: 414px)
and (max-device-width: 736px)
and (-webkit-min-device-pixel-ratio: 3)
and (orientation: landscape) {

}

This PR has received new commits.

CC: @andrepereiradasilva

This PR has received new commits.

CC: @andrepereiradasilva

I'm a little confused about github

the first time is normal.

bottom line is, when you change any file in your patch-1 branch (the branch you originally used to create this pull request) in your joomla-cms fork repository they will automatically be in this PR.

this is your patch-1 branch https://github.com/ucfnet002/joomla-cms/tree/patch-1

This PR has received new commits.

CC: @andrepereiradasilva

I deleted line 1329 and it seems to work ... here is my " administrator/templates/isis/css/template-rtl.css
": ucfnet002@e4446c5

@ucfnet002 run php build/generatecss.php from command line

My dev environment isn't set up yet. i did the changes online in github. maybe someone can run this for me while i try to set up my local github repo. thx :-)

This PR has received new commits.

CC: @andrepereiradasilva

I have tested this item successfully on 1c44b06

I have tested this item successfully on 1c44b06

RTC - thanks

I have tested this item unsuccessfully on 1c44b06

Modal scrolling is broken on iphone and safari.
The reason i added overflow auto is due to a known issue with bootstrp 2 and 3. (Not fixed today) and because of a webkit issue.
The only known way to fix it is to force overflow.
I'm sorry, currently on holidays and with only my iphone, but i've alredy work on an improvement of my previous PR for 3.5.0
And could check it when back next week...
Sorry for timing...

Removed RTC status

Imho, this should be added to blockers as batch is badly broken since 3.5.0

@infograf768 i've worked on a redo of BS issue fix, and this one may solve batch issue too!
And the PR will be ready today (i'm testing again it, on different screen sizes and devices...)

Will inform about this PR in all issues related to the modals ;-)

@infograf768 @ucfnet002 @brianteeman @wojsmol @andrepereiradasilva a PR is ready to be tested as a redo of PR 9140 to fix scrolling of Bootstrap modals on small devices and iOS as well as fix for batch dropdown issue: #9817
;-)

Closing in favour of #9817 Please test

@brianteeman @rdeutz please remove the milestone as it get never merged