I’m having a problem related to the rig of 2 cogs.
In Blender, I’ve modeled 2 cogs, and rigged them making them under the same rig.
As you can see in the video, the first and second cog bones are disconnected.
When I import them to Roblox, the bones are off centered and an extra bone appears where the previous disconnected bone was, making the cogs to not rotate properly.
Once I had an issue where an imported animation would be unaccurate, maybe this fix works for you too. All I did was shrink the model a lot inside blender and export it again, it seems like roblox doesn’t handle scaling big rigs well. Was the rig really big when you imported?