I'm struggling to find a reason this won't work how I believe it should. So, I create an assembly and I want all of my parts in that assembly mated to the origin. I get all the parts into the assembly and think that I can be clever and choose "Multiple Mate Mode":
Then I choose the assembly origin in the top box and all of the part origins in the bottom box, making sure that "Coincident" is selected. Well, that doesn't constrain my parts fully. Can anybody explain why this doesn't work as I expect it should? Is this a bug, or am I missing something?
I have attached an assembly. The top part was mated via Multiple Mate Mode, and you can see it can move around. For the other two parts, I deleted the Multiple Mate and mated them manually. You can see they are fixed.
Edit to add: I'm bumping this thread because I posted it in the evening and only got one reply...