Guild Wars 2

Hi, I skimmed through but couldn’t find if this was brought up before, so here it is. Yesterday I played AC p3 and when the little Asura NPC turned the party into ghosts, my engineer got all the right-side skills locked. When I drew the cursor over skills 6-9, the message was “unable to use while transformed”. This has happened to me once before (about a month ago) on this same character. Usually I take my guardian to AC and have never encountered the same problem with her.
Luckily, we managed to defeat the Colossus despite me not accessing crucial skills, but that was due to a good party.

Is this an engineer-specific thing that was tweaked in myriad AC updates (if so, it’s rather inconvenient), or is it a bug?