I just checked and the version 20 roof accessories migrate automatically to 24 objects so long as the 24 accessories library is loaded.
No need for migration libraries as such.
You missing objects folder is greyed out.
When I have missing objects it shows solid and when I select it it shows the names of the missing objects.
What happens when you select that folder?
Usually if nothing is miss, you will not see that folder at all.
I have never seen it greyed out.
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