Steps to reproduce the issue

1. Create a repeatable custom field linked to an article.
2. Add a form field with parentheses as part of the name. For example, Caption (optional)
3. Save, and create a new article.
4. Add content to the custom field.
5. Press save.

Expected result

I expect the save button to work.

Actual result

Nothing happens, I can only close.

System information (as much as possible)

MacOS Mojave 10.14.5
Joomla 3.9.8
local dev server on PHP 7.2.14

Additional comments

It's definitely the parentheses, as changing the field name to Caption - optional makes it work

Console spits out this error:
Error: Syntax error, unrecognized expression: #jform_com_fields__insights-images__insights-images0__Caption (optional)-lbl jquery.min.js:2:12666