Just updated to Sonoma (Mac) not sure if this is related.
Any doors and windows that were placed in my project are missing from the library. Library Manager shows them as "missing objects" but the rest of the AC26 library has loaded correctly. For example all furniture is still present. All doors and windows that were not placed in my model are showing up correctly in the library.
I have uninstalled and reloaded AC26 and downloaded the latest updates.
I have unloaded and reloaded the AC26 library.
I have re-opened the file, running "open and repair".