dunno what caused this but i partner button wasnt doing anything
according to training mode it was accepting the input and just… not doing anything
i restarted my wii and it works again
odd
And do you know how to recreate this?
This same thing happened to me with my fierce attacks, and I realized that the WiiMote was between the couch cushions with the A button held in. 
That would register your input and not allow you to swap, but from your explanation it is hard to tell.
Strange to have to worry about this dangling controller while you play.
It tends to happen with the Classic Controller. I have no idea why. If it happens, unplug it and plug it back in.
scheiss hit the nail on the head, smae thing happened to me, and I realized the wii mote had fallen and a button was being held down on it.
Haha, happened at a tourney I was at with my wiimote in my backpack. I felt really bad. At the same time, I’ve been wondering when fighting games are going to have some kind of option to keep other controllers from syncing mid-match. Didn’t that fuck up a Tekken tourney way back? On a ps3 i think…