Take 2 parts, weld one to another using Motor6D and then select the motor and press ctrl d
I’ve had this happen twice until I got too pissed and stopped until my friend confirmed it wasn’t just me…
just a habit I have duplicating instead of making it new…
Can confirm I am having this issue on the latest version of ROBLOX Studio (0.249.0.77601), but it doesn’t happen on the previous version (0.248.0.76966) – it must have been caused by something that was changed in the latest build.