Weird issue: All my State Machines stop updating system-wide

I’m experiencing a very strange problem in the latest version of the engine (4.12.3). My game is Blueprint-only.

It only occurs in this specific boss level, to my knowledge. For some reason, at random times during the level, all StateMachines in AnimBlueprints across the entire game will stop updating. They remain stuck on whatever State they were in, even if the variables controlling their Transition Rules have changed and should have triggered a state change.

What’s even stranger is that:
-The problem occurs completely randomly, but only in this level
-The variables controlling my States do appear to be updating correctly in the AnimBlueprint. The StateMachine just isn’t switching to the new state to reflect the new values.
-The problem becomes permanent unless I relaunch the whole game or editor. If I play the level with the options “Play->New Editor Window” or “Play->Standalone Game” in the UE4 editor, the effect becomes semi-permanent until I close the entire Unreal Editor and relaunch it. Once I’ve relaunched the entire editor, the problem is gone and my states work again.
-If I DON’T close the editor/game, then if I leave this boss level and enter another one, the problem persists even in other levels. Nothing changes animation states anymore, globally, until the game or editor is completely restarted.

Because the problem is happening to ALL AnimBlueprints in the game I am having a rough time debugging and figuring out where to even start looking for the cause. I have no idea what could possibly be causing ALL AnimBlueprints to screw up like this. It sounds like it could be a bug in the engine itself. Has anyone else encountered a problem like this? Any workarounds you can share? Is there’s a way to “reset” or trigger the StateMachines? I’ve tried setting the AnimMode to Asset and then back to Blueprint to see if that would reset the but it doesn’t. And even if there is a way to do this I don’t think it would be feasible for me to have reset the States for every little animated thing in the game.

I’m posting this here in addition to the AnswerHub just in case some other devs here might be able to offer a workaround. My game is inching closer to being finished but this problem is unfortunately putting a halt to everything.

I’m quite new with ue4 but i have the same problem. After updating to 4.12.3 the state machine of my character has stopped working. For some days after update has had some trouble and paused randomly and now for every simulation after one second and forever. I thinked was for some variable deleted but all seems ok and i was working on umg and not on character. It seems to be something releated to update.

Sounds like a very annoying issue and since this even could be semi-permanent it looks like an eninge bug to me either. Don’t know how you did get there but probably you could take a look with “stat anim” in the console if you get this issue next time and see if you get some weird values, like don’t know …a huge amount of call counts at one of those cycle counters or something like this. You could of course even remove one actor after each other if it only occurs in a special level but if the issue only happens random this would be a huge pain as you could not be sure if you found it just because it works for now.

Are you using multiple state machines at the same time? I’ve had trouble with that approach because if one of the state machines blend out. It will get stuck in which ever state it was currently in. The next time it resumes ticking it will start from that state. Depending on your design the controlling/transition variables might no longer be valid at that point.

There doesn’t seem to be a way to reset state machines or atleast I have not found one. You should either ensure all state machines are always blended into the final animation pose (expensive) or just use one state machine and move everything else to montages.

Glad to know I’m not the only one experiencing this, I’ve scoured my Blueprint scripts trying to find a cause, and also have gone to extreme lengths to optimize everything just in case it’s a performance thing, but nothing helps. :frowning:

Thanks for the tip, I didn’t know about the stat anim command. Unfortunately all the callcounts seem… normal? Most in the list that comes up are pretty low, like 10-40. Not sure, maybe someone else can judge better:

All of my AnimBlueprints use only a single state machine each. So yeah, unfortunately that’s not the problem here :frowning: Thanks though.

EDIT: After some thought, I’ve decided to just scrap the level + boss and redo it completely. It’s gonna be a lot of work but I’ve already wasted too much time trying to fix this. Thanks to those that tried to help, regardless!

I have not fixed the bug but i understood where it resides. I’m not a developer but an artist and i am not able to investigate further, but i created a new anim blueprint, a new character blueprint and finally a new level. The only option that has put things in order is creating a new layer so i assume that the problem lies within the layer itself. I read something about not edit options in the editor when it has to do with a state machine, and I might have done something like this. My game is still composed of only one level and therefore I would blame the blueprints character or anim. In my opinion this is a bug because anything i have changed in the editor options was only temporarily and caused a permanent trouble but my experience is not enough to be certain of this.