I did try to look for something similar before posting but couldn't quite find the right words to search.
But to sum it up, i'm sure its not my addons because i had done 3 other trials before this one and I've never encounted this problem before.
This is on the PC-EU megaserver on my stamina dragonknight zaizah.
So here's the rundown on what happened, i joined a group for normal cloudrest we go and kill Galenwe and then run to Siroria.
Well while waiting for the rest to get here, i was waiting just on the step where the barrier spawns when someone starts the fight. This teleported me into the battle as it usually would but this time it bugged out, I had no use of any abilities, i could not swap weapon bars and even rolling, jumping or death and being resurrected wasn't even enough to fix it.
The only option i had was to leave the instance all together where a zone jump had fixed the issue.
I'm hoping it was a one off, but i /bug reported it anyway to be on the safe side.
Here's a quick video (no sound) of me trying to use my abilities (with the keybinds and the mouse too)
Player since Beta (Tenth Anniversary Badge!)
PC - EU (2316cp)
Arcthulhu - Stam Arcanist - DD
Zaizah - Mag DK - DD
Hermora the Explorer - Arcanist - Healer
Step Vrol Im Stuck - DK - Tank