It occurs uncommonly, but commonly enough to sometimes notice it.
There are 2 variants for this ''error'' action.
1st: You fish, you get the successful animation, character does the all good animation of pulling off something off the hook, yet the hook remains the same one you attached (bone for example), with the same worm, completely undamaged. No item retrieved during the fishing attempt.
2nd option: You fish, successful animation, character pulls off something off the hook, hook and worm remain, BUT CHARACTER IS NOW STUCK ON THE SPOT, so moving makes you basically be glued to the spot, you cannot switch items, cannot switch anything.
Sometimes you can JUMP on the spot to unstuck, but that's 3/10 times, mostly you'll need to relog.