When using a tablet, have you ever not been able to sign on with just the mobile version?

So you’re saying, the “Mobile” (app) version does not work on the mobile device, but the “Desktop” via a browser works fine, on the same mobile device?

Yes on the same mobile device.
Whenever I use the tablet, before absolutely anything, I click on Safari app, or Chrome app, it gives me Google, I search for Fluther.com, (not iFluther) Fluther.com mobile version shows up by default, most of the time. Signing in hasn’t been a problem either way, Mobile version or Desktop version (except a few months ago when everyone was having a problem posting a question (OP) and a few other things) But on the day that I posted this question I coudn’t sign in on the Mobile version. I tried a few times. I switched to Desktop, no problem.