Duplicate button not working?

WP: 5.8.2
Waiting: 0.5.4
Browsers: tried on Chrome, FF Dev Edition

I’ve been using waiting for a couple of weeks now, crated a few timers, edited, put them om a blog etc. No problems there.
But then, I went to duplicate one of my existing timers, because it is very similar to the existing one (in fact, only changing the day) and the “Duplicate” button… does nothing.
No error messages, no console warning/errors, just not doing a thing. It’s as if it doesn’t attach an event to the butotn.

Am I doing something wrong or is there a problem?