ok, can you;

1. check if wp-content/plugins/async-javascript/assets/lib/chosen_v1.4.2/chosen.jquery.min.js is available on the server (it should)
2. check if you can load [yourdomain]/wp-content/plugins/async-javascript/assets/lib/chosen_v1.4.2/chosen.jquery.min.js in a webbrowser (it should)
3. go to Async JS settings while keeping an eye on the network tab in your developer tools; is it requested (it should) and do you see a 200 (or 304) HTTP response code or something else?

frank

also when on the async js page? in that case there’s no reason why you’d get that error message really as it’s that file that defines the jQuery .choosen function …

so …
1. what browser are you using?
2. are there any other errors on the console?
3. are you running any other plugin that is changing the way JS is loaded in the backend?

(going to get me some sleep now, but I’ll make sure to follow up on this tomorrow)

OK, so _maybe_ it’s a problem that is specific to Safari, could you test in Chrome or Firefox for MacOSX?

OK, can you try https://harvesthq.github.io/chosen/ (the Chosen demo page) in Safari to see if that works?

OK, so an issue with the Chosen implementation on Safari … I’ll have a look at the code and try to find someone on MacOS so I can test myself.

Could you make a screenshot of what you mean when writing “I lost the button in the “add entry” section.”?

OK, so the problem is not (only) on the AsyncJS settings-page, that’s ugly. I’ll get working on a fix right away!