Great Frank. The update works as intended without modifying the bootstrap css file.
Ideally I guess it should be enqueued on the frontend only in most cases Frank. We also use bootstrap on the backend for administration of the database of our voice samples.
– And thank you very much for a great plugin!
Another reason for the advanced options not showing in AO is if the site is using bootstrap.css. In my case Commenting out this part .hidden{display:none!important} in the bootstrap css file made the advanced options (and WordPress Screen options/Help) show up. In our case we use bootstrap to generate a filtered list of voice samples: https://voiceresort.com/voice-over-speak
