Lolwut? What kind of edit did you do? It is only expected to disappear when you place it in the inventory. Should be reported as a bug, not here.

I simply added new memory to the Sim, lol. I have no idea which mod to report it on.

My mod as the error occurred while interacting with it, with as many details as practical and the error report text file if available, or generated manually as soon as possible after the event. And the version number from About since I updated it quite often. The mod does some deletions to get names on screen. All fridge inventory and Badges when bringing up the menu, and the memory itself when adding. But it's not clear how it could lose track and delete another object that existed earlier, and reproduce the error.

You could look in OETreeDelete.xls and see what code made the deletion. It shows the line number too.

If the couch still exists but is invisible, then I have no clue, as I don't do that.

I think this thread is about quirks that exist in the core game itself.

Deceased Sims can have their lifetime want fulfilled, and if their ghost happens to be on the lot at the time then you get the pop-up notification for it and the aspiration points appear above their head. I have long suspected this was possible as I've seen ghosts have wants fulfilled (like having a grandchild or a teenage relative getting a scholarship) but today was the first time I saw them have a LTW fulfilled. My Sim died without fulfilling his LTW of having six grandchildren, and his ghost appeared on the night when that sixth grandchild was born.

Related- if your LTW is to have a Golden Anniversary and your husband dies during the party, the LTW is still fulfilled and you can still have a Roof Raiser