It was working for me all afternoon yesterday. Then, I logged in my second D3 account. Since then, nothing on the xp per hour ticker. I tried deleting all of my settings, etc to get rid of the original account info but still no go. Going to try a completely fresh install and see if that fixes it.
Edit: Just tried the new Beta. I haven't verified this yet but my barb on account #1 has less than 100 Paragon levels while my barb on account #2 has over 100 Paragon levels. Possibly xp counter quits working if you are over 100 Paragon level? Will swap to other account in a bit and see if this is the case.
Edit 2: Confirmed that it's working for my toon that has less than 100 paragon. Not for my toon with greater than 100 Paragon.