@blebbens Does the problem still exist? I just tried with the lastest version of MM & the module (which I’m also the developer of) and also configured your PWS and it worked just fine on my mirror.
If it does not work, could you please open the MM on your web browser and report the JavaScript error message you get there (e.g. follow https://codex.wordpress.org/Using_Your_Browser_to_Diagnose_JavaScript_Errors#Step_3:_Diagnosis to find the error message)?