Installed iOS 8.3 and now I can't sign into iMessage or FaceTime with my Apple ID

That's too bad. Do you have a question?

I am having this issue on my IPAD running 8.3. Can't log in to facetime or iMessage. Cannot turn the apps off and back on (per online suggestion).

I assume Apple has decided that NO ONE should be able to turn these apps off.

Does anyone know whether Apple has acknowledged the issue or is doing anything to resolve it?

Hi, try backing up your iPhone to iTunes, then doing a restore from back up. When ever I have an issue with my iPhone I do this and it solves the problem. Good Luck!