Component Copy Leaves some Geometry behind

Arch lattice and teeth.skp (618.9 KB)
I finally got my lattice work completed, though I will add the cog elevator later once it’s in my main Arch.
But when I tried to highlight and make the attached arc into a single component that could be copied into my main sketch, only the red lattice work copied over. I lost the blue base and the internal tracks, even though they appeared to be highlighted along with everything else to be copied.

A possibly related issue is that my main Arch starts flashing when I add this component to it. Does this mean my arch is becoming deformed or…?

…uh, never mind. I figured out the problem and moved the arc into its permanent home.

I’m still concerned about the occasional flashing and the slowdown of the computer in general though. Is there a way to clear memory cache of old moves and history?

My main structure has barely begun to get everything its going to get.

Yes, saving the model purges the undo stack.