I first got a message saying too many devices signed in. The window gave me an option to sign out so I signed out of all devices. Then, I have followed the complete uninstall guide from support chat. I did an advanced reinstall. Now it says "there is a problem signing in" in red no other explanation. And my iPhone and iPad that I signed out of now won't sign back in and say too many devices but no devices are in the list. I have signed into dropbox.com/account/security and removed all devices. This doesn't help either.