It started happening during arena queues for me, not sure if it happens with BGs too. Have to reload to be able to join, right-click enter battle on the icon is also buggered.

I also am having this issue with latest versions of both SafeQueue (v5.1) & Questie (v6.5.1)

3 observations from my experience:

1. I just encountered another error preventing the SafeQueue button from working, this time with TomTom.

2. In retrospect, I should have mentioned this in my initial commnent. Every time the SafeQueue button didn't work (which was at least 5 times), neither did the default BG queue button in the minimap. There were yet still other times when the SafeQueue button worked, even with Questie enabled.

3. Prior to installing SafeQueue 2 days ago, I always had to use the BG minimap button, because the default button never works (which is well known of course, hence the need for SafeQueue in the first place). I honestly think the BG minimap button is itself experiencing a taint error that is unrelated to SafeQueue, because IIRC I had to reload my UI a couple times prior to using SafeQueue, because both the main Enter Battle button and the BG minimap button were broken.

EDIT: I would like to point out that the SafeQueue button is failing much less frequently with Questie disabled. After playing with SafeQueue with Questie disabled, SafeQueue has only broken once out of dozens of queues, and that was the TomTom error, which I have yet to replicate.

EDIT 2: Nevermind, TomTom error has happened a few times now. Still appears to break less frequently than SafeQueue did with Questie, even with my relatively small sample size.

EDIT 3: Now seeing errors with ArkInventory breaking the SafeQueue button too, apparently. It's more likely a generic taint error that is breaking the SafeQueue button, since the default UI's BG minimap button breaks in these cases too.

also having this issue