Bug A crash when using Playables API

I'm not sure, if I should post it here or in the Timeline section. We are not actually using timeline, just doing very basic sprite animation with playables.

So, one of thousands of players of our game has been reporting frequent crashes. The exception is
c0000005 (Access violation), here are some stack traces from crash dumps:

Spoiler: StackTrace 1

Code (csharp):

1.  
2. UnityPlayer!AnimationMixerPlayable::MixerProcess+0x10c
3. UnityPlayer!AnimationMixerPlayable::ProcessRootMotion+0xbb
4. UnityPlayer!`anonymous namespace'::ProcessPlayableGraph+0x26b
5. UnityPlayer!Animator::ProcessRootMotionStep+0x23e
6. UnityPlayer!Animator::ProcessRootMotionJob+0x74
7. UnityPlayer!UnityEngine::Animation::BlockRangeJob<Animator::AnimatorJob>::Job+0x38
8. UnityPlayer!JobQueue::Exec+0x52
9. UnityPlayer!JobQueue::ProcessJobs+0x127
10. UnityPlayer!JobQueue::WorkLoop+0x40
11. UnityPlayer!Thread::RunThreadWrapper+0x58
12. kernel32!BaseThreadInitThunk+0x10
13. ntdll!RtlUserThreadStart+0x2b
14.  

Spoiler: StackTrace 2

Code (csharp):

1.  
2. UnityPlayer!Animator::ProcessRootMotionJob+0x74
3. UnityPlayer!UnityEngine::Animation::BlockRangeJob<Animator::AnimatorJob>::Job+0x38
4. UnityPlayer!JobQueue::Exec+0x52
5. UnityPlayer!JobQueue::ProcessJobs+0x127
6. UnityPlayer!JobQueue::WorkLoop+0x40
7. UnityPlayer!Thread::RunThreadWrapper+0x58
8. kernel32!BaseThreadInitThunk+0x10
9. ntdll!RtlUserThreadStart+0x2b
10.  

Spoiler: StackTrace 3

Code (csharp):

1.  
2. UnityPlayer!PlayableTraverser::CreateNewVisitorInfo+0xd2
3. UnityPlayer!PreOrderPlayableTraverser::RecursiveVisit+0x9e
4. UnityPlayer!PreOrderPlayableTraverser::Traverse+0x25e
5. UnityPlayer!PlayableOutput::PrepareTraverse+0x137
6. UnityPlayer!PlayableGraph::PrepareFrame+0x13b
7. UnityPlayer!PrepareFrameJobFunc+0xb6
8. UnityPlayer!JobQueue::Exec+0x52
9. UnityPlayer!JobQueue::ProcessJobs+0x127
10. UnityPlayer!JobQueue::WorkLoop+0x40
11. UnityPlayer!Thread::RunThreadWrapper+0x58
12. kernel32!BaseThreadInitThunk+0x10
13. ntdll!RtlUserThreadStart+0x2b
14.  

The game is in pixel-art style. The way I am using the Playables API is I am connecting all the possible animations to one mixer. Whenever I need to change the current animation, I am setting its weight to 1 and the weight of the previously active animation to 0. Sometimes more animations need to be added later - then I change the mixer's input count and connect the additional animations. I don't inherit from PlayableBehaviour anywhere.

The crashes don't seem to have a pattern, at least the user couldn't describe one. I don't think submitting a bug report will help as it is probably not reproducible except on a particular user's machine. This is a long shot, but does anyone have any ideas about what could be causing this issue?