When there are an issue and teloadUI doesn't seem to resolve it, then log completely out of game (quit) and restart game client again to force both game client to read files into your RAM and force a new connection with log in server to get your charachters data updated.
Make sure you have min. 250 Gold in player Inventory for charachter in case you might have moved Gold to Bank.
Check that you pick an upgrade/are training something that is below 60.
I know you said that you would get a message if you try to upgrade something that are already at 60, but better make sure you are really picking the right training that is below 60.
Change mount in Collection, if you more then one mount and make sure you have put it into active mode.
If nothing that have been suggested work, then your only option is to create a ticket with CS.
if you play in PC platform try quick fix (it might not help, but would bit consume much time)
1. repair game client - click Game Options drop-down list, select Repair. Wait until complete.
2. fix game shaders cache - rename ShaderCache.cooked into ShaderCache.bak in your \Documents\Elder Scrolls Online\live folder. next time you launch the game. it will be recreated.