I have a problem with the Deform Mesh modifier in Blender 2.83 (which I suspect may be a bug).
I created two simple rigs in exactly the same way to demonstrate this, one in 2.79 and one in 2.83.
In 2.79 the rig works perfectly.
The tank tracks follow the Curve modifier nicely.
If I follow the same steps in Blender 2.83 using the same modifiers, same process, I can get the tracks to turn just fine...
...but when I use the Deform Mesh modifier I get this:
You'll notice that the tread pieces that are vertex parented spasm on rotation.
But this only happens when it's animated. In the same file, (the same file!) if I move the Mesh Deform controller and then MANUALLY rotate the tracks I get this instead:
Personally, I think it's a bug, but I'm open to get community answers before I report it as such. I'm also very open to it being human error as well.
Let me know what you guys + girls think?
A link to BOTH files (from the images) is here:
TankTracks - deformation 2-79.blend
TankTracks - deformation 2-83.blend