So, I think its pretty safe to say that the whole Raid UI is bugged as hell at the moment. I know that we're not supposed to make several bug reports per issue, but most of the ones done have been ignored and this problem has been here since the beggining.
Things that need to be fixed:
Raid Difficulty and Size - Currently really fucked up. You can't change difficulty unless everyone in the raid changes it too, as for Raid Size(on legacy raids), its almost impossible to change it from 10Man to 25Man, no matter how many times you try this seems impossible to be done, making some raids unacessible.
Entering Raids without being in a Raid group - In Mists of Pandaria, Blizzard introduced us a new way to enter raids without the need of actually being on a raid group. At the moment this doesn't work, the only way to enter in a raid is to be with someone else in a raid group.
After changing the loot allocation while in a raid group your UI becomes completelly bugged out and you cannot change anything related to the party or actually leave it without using a script. You cannot right-click your portrait again until you leave your group, you can't kick people through the raid panel or anything else.
(this one I'm not 100% sure if its global or not, this happens to me) The default Raid Frames seem to be locked in place even after clicking on the unlock button.