Oh interesting - I’m not completely sure why that would be the case. I use ViolentMonkey, but I tried it with TamperMonkey v4.8.41, and it seems to work for me.
By chance, do you use www.kaniwani.com instead of kaniwani.com? (I actually don’t know the difference between them, but I use the latter; I also can’t seem to log in to the former at all)
I modified the script’s @match to use a simpler form. Maybe try the newest script version and see if that works? KaniWani audio