For those having the same problem, also discussed in older topic:
v2.users.{id}.activity
I opened a ticket for this and apparently These trigger don't fire for users that have not been on queue yet (new users) or users that were not on queue for more than 60 days.
Response from engineering:
I found an engineering case that states
...have the noted non-working users ever gone On Queue? If that has never happened, this event will not be published for their user. I imagine if they’ve not gone On Queue in the last 60 days this wouldn’t work either as that’s when routingStatus TTLs. This has come up before and was confirmed by the WFM team as intended as the event was created for those types of applications and not for non-ACD users.