I had a really similiar situation and syncing all the needed table in the definitive one’s solved all my problem!
What’s your situation @Association_A_Million_Dreams?
This looks like a 3 doc setup which is tough to make work because cross-doc tables are actually their own table that pulls in information from a main table. These are not necessarily linked tables.
If you have a main doc with a main table, then add two more docs, “Doc 1” and “Doc 2” that read from it, “Doc 1” doesn’t know that “Doc 2” is using the same information. It only knows about the main doc.
So it takes some planning to make sure all items are connected properly.
I also had a really similar situation, where some synced columns say “Row not find”, even after syncing all the needed tables. It seems to be happening when the source column has a lookup from another table, but with a formula from a third table (Exactly like @Juan_Luis_Chulilla explained it).
What I did instead is removing those synced columns, and add new columns with lookup formulas like in the source document. This isn’t convenient but it does the job