Although I'm not aware of official documentation on this point, I believe that in a Quick Base Action, changes can be detected only in:
- Data-entry fields, i.e., those that can be entered manually on a form for the table
- Formula fields calculated from data-entry fields.
This excludes:
- Lookup fields
- Formula fields that are computed from lookup fields.
In effect, the Quick Base Action can only be triggered by changes made directly in one of the table's records, not indirectly by changes made in other tables that cause lookups to change.