Not into the customizer but in menu “design” an there you can control your text widget without problems. I’ve got much plugins activated so for now I can’t test it. Sorry
Ok I just tested Black Studio TinyMCE Widget with GP premium activated and was able to edit text widgets in Dashboard > Appearance > Widgets no problem.
I think it’s some other plugin that’s causing the problem so test out if you get a chance!
For me it won’t work.. I only activated these three and I’m not able to edit it.
I only deactivate Forget About Shortcode Buttons so I won’t have this problem π