Steps to reproduce the issue

1. Create a page in SP Page Builder. Save and publish the page.
2. Create a menu item, type SP Page Builder >> Page.
3. Click "select" button to open the page list to select the item for the menu item.

Expected result

Modal window opens to select the page for the menu item on clicking "Select" (highlighted illustrated below)

Actual result

Cannot select the SPPB page for the menu item (modal window doesn't open). Menu item can't be saved as that field is required.

System information (as much as possible)

Joomla 4 Beta 7 (https://github.com/joomla/joomla-cms/releases/tag/4.0.0-beta7)
Helix Ultimate Template Alpha 4 (https://www.joomshaper.com/blog/helix-ultimate-2-0-alpha-4)
SP Page Builder (Pro) 3.7.9 (https://extensions.joomla.org/extension/sp-page-builder/)
PHP 7.4.11

Additional comments

I'm not sure that this is a problem with this Beta 7 of Joomla 4 or if it's SP PB or the Helix template.
I've posted the same query on the developer's site (JoomShaper): https://www.joomshaper.com/forum/question/1468 and also in Joomla Forum(https://forum.joomla.org/viewtopic.php?f=715&t=984578)

Thanks.