Happens to me as well on PS4 since update 2.48..
Especially in Battlegrounds and Dungeons, my Arcanists Ultimate will not work, and occasionally other abilities as well. Even lightning heavy attacks won't fire sometimes. I have to swap bars then back again.
Best for me not to do dungeons, but I need to level up Undaunted.

Thanks.

Seems to be a problem with targeting.
I've been having problems with heavy shots not connecting, you just stand there with a bit of a twitch, especially after using overload.
Trying to get a lock on to get shots off is getting worse.

I was in a dungeon group two days ago and noticed ability 2, and sometimes ability 4 didn't cast. I tried spam hitting those keys and it didn't work. Group was wondering why my dps was off. I told them. They said it's a bug.

Forgot to mention. PC NA

Lots of us in our recent gs prog experienced this daily. Not the one where you literally can’t cast at all, but the one where your client says you cast but the server thinks you didn’t and you have to do it again. And again. And again.

In those cases, to me, it feels like a bit better version of Cyrodiil, where you often see the client send commands (the skill icon “depresses” on the screen) but the server doesn’t seem to process them correctly. ZOS did acknowledge that the performance issues being observed were making their way into PvE. They said their code rewrite didn’t make much progress but claimed the hardware replacement did, except we’re back to communication between client and server degrading. When blockcasting on trash pulls, as much as 25-50% of my dot casts were not being processed: caltrops, spear, orb, solar barrage, hail, cloak. It isn’t class specific. It isn’t specific to dots that have to be placed on the ground vs sticky dots on self vs dots that can be cast anywhere. They all have trouble.

It does feel like certain skills are particularly problematic: Spear frequently won’t cast properly, for example, which supposedly got a fix for controller a while ago, but then they had to revert some unspecified changes because they broke Break Free on controller, and I think we lost the Spear fix because of that. Beam also frequently just doesn’t cast, so I have to make sure to put myself in a position where I can see whether it’s gone off. I can’t rely on my skill bar, since the icon visually depresses on my screen but the game doesn’t get the message. I sometimes even get the audio and see a cast bar from Combat Metronome, so I know the message was sent on my client’s end. For some reason the server is either not getting it or rejecting it.

My ping is typically between 60-80, including during these situations, and there’s no issue with packet loss when I test it.

I just had this problem not 10 min ago. Xbox one controller on PC. Could fire my ult and 1 skill. The rest were stuck. Had to leave a dungeon because of it.

Not keybind, at least on my oakensorc. Still have 3 left but still can't fire 3 skills

What else is new lol this is an issue for me a lot of times on ps/na. Im on a 5 and i still encounter this even with a good internet connection attached to lan.