I have a master assembly BOM in a drawing and also inserted several views of sub assemblies. When I do callouts on the sub assemblies only the ones that aren't set to treat as a single part work. The others simply get a red circle with a question mark
I inserted first an summary BOM into the drawing and made some call outs. There are also call outs from within the subassemblies.
then double clicked on the BOM and changed the BOM to standard:
At the single parts of the subassemblies the numbers turned to question marks. The parts are not listed in the BOM
If i now insert a new call out it will get the number from the corresponding BOM:
But you have only one active BOM on the sheet regardless how many views you insert, the standard BOM with your subassemblies or the summary BOM with the parts...