I have a TinyMCE editor in a Fancybox 5 (inline) dialog.
The editor itself works fine, but when I click the <> (source code) button, the cursor doesn't appear in the box and I am unable to edit it. Interestingly, the Save and Cancel buttons are still clickable.
I found this answer on StackOverflow - https://stackoverflow.com/a/18209594/1333416 - but it relates to a different version of TinyMCE and Bootstrap.
Here's a pen showing the issue:
