I am afraid you will have to open each section/elevation/detail/worksheet etc. manually, turn all layers on and see if you can spot the missing objects.
Unless someone knows something I haven't realised.
The good thing is if you are just going to delete the objects then it really doesn't matter as they won't be showing.
So if you can put up with the missing objects message then all is fine.
But if you are like me I hate having missing or duplicate parts even when they aren't going to affect anything.
Especially when others will be working on the file.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11