I always wondered why I couldn't log in using Voyager either. I also use an auto generated password from my password manager, could be related to lengths or a certain special character.

I also had problems logging in with sync. For me, it was the instance input.

Somehow, after i filled out the instance, username & password inputs, the form blanked the instance name when submitting.

I didn't notice at first.

Entering the instance name again made it work.

My password is >!long!< too, but idk if it's as long as yours