Get "Loading" message or jumbled up GUI

Thanks for making the module.

I use D8 Editor Advanced link together with D8 Editor File upload and sometimes it doesn't work, it just says "Loading" when I click the button. Other times the GUI appears, but seems to be lacking some CSS... (see the image)

I am getting this notice in the logs:

Notice: Undefined index: #group in editor_advanced_link_form_editor_link_dialog_alter() (line 82 af /data/www/website/modules/editor_advanced_link/editor_advanced_link.module).
Notice: Undefined index: #group in editor_advanced_link_form_editor_link_dialog_alter() (line 82 af /data/www/website/modules/editor_advanced_link/editor_advanced_link.module).

I use Bootstrap, and there has been a previously issue, where users just get a "Loading" message when clicking the image icon, perhaps this issue is related? Editor routes don't use the ajax_base_page theme negotiator