Bug Timeline Crashes Editor on starting VFX after last package update

I made a Timeline which plays some sounds, some animations and enables various VFX Graph Objects. 95% of the time, it crashes since I updated the packages (all packages. including timeline and probably the HD Render Pipeline / VFX Graph)

Log says:

Code (CSharp):

1. Exception: VFXSpawnerState : SetWrapValue is reserved to CreateWrapper object
2.   at UnityEngine.VFX.VFXSpawnerState.SetWrapValue (System.IntPtr ptr) [0x0000c] in <a69dc1db85a441c59c35d8730b5f7877>:0
3. (Filename: <a69dc1db85a441c59c35d8730b5f7877> Line: 0)
4.  
5. Exception: VFXSpawnerState : SetWrapValue is reserved to CreateWrapper object
6.   at UnityEngine.VFX.VFXSpawnerState.SetWrapValue (System.IntPtr ptr) [0x0000c] in <a69dc1db85a441c59c35d8730b5f7877>:0
7. (Filename: <a69dc1db85a441c59c35d8730b5f7877> Line: 0)
8.  
9. * Assertion at ..\mono\metadata\loader.c:2253, condition `data != NULL' not met

It never happend before the update. I didn't touch the timeline or any of its graphs.
Code for triggering the timeline (simple box collider trigger, telling the timeline to Start) also wasn't changed.

It clearly has to do with the update because nothing else changed.

I post it here because I googled "Unity "SetWrapValue"" and this only led to the CSharp Reference of Unity, so if anyone else discovers this but, he may end up here on this thread.

Unity Version: 2020.1.2f1