2022: Sorry to notify you late, but please try again!! :)
2021: Hi! the mouse wheel shortcut assignment is a (the only) known firefox-bug yet (already in our Github Issues). Please report every other bug you might find. Do you know scroll wheel shortcuts from our Chrome version (or why would you miss it)? Our UI generally runs well in all Browsers and deserves 5 stars.
(Why do you do restart the browser? if you want you can reload any extension alone but it shouldnt be necessary) thanks!