Edit linked bug, or senior moment?

I'm fairly sure (but not 100%) that if I used edit linked parts to select several prims in a multi-prim object, then unlinked it used to separate the prims I'd selected to be single prim objects, but would leave the rest of the object properly linked together.

Now, if I do that the whole linked set falls apart to single prims.

If it's not just my memory I'll happily bug report it, if it's just a senior moment, sorry for wasting your time!

That sounds like a bug. I did a quick search of our known bugs but did not find it. If I can reproduce the problem I'll enter a new bug.