At the "Publish" step, if we click on "record more files", nothing happen.
Actually I just tried using Firefox 66.0 on Mageia Linux 64-bits and it worked. So it seems the problem occur sometimes, probably on some webbrowsers.
Problem occurs on Firefox 66 on Ubuntu 64bit – so it's apparently not due to browser-version. Maybe an Addon? I'll try out next time.
I can reproduce the bug in Firefox 70.0.1 (64-bit) on MacOS Mojave 10.14.6.
As I'm currently rewriting the whole view and events managment parts of the RecordWizard by switching to vue.js (see T248983), it may fix this issue. I'll keep an eye on it.