We had a similar use case with freight tracking checkboxes against closed shipments. UD fields would not update once the shipments were closed. I ended up using data tags against the shipment header which don’t have these limitations:
Data Tags (SYSTAG) - an under-utilized feature in Kinetic
They can be added / removed via BPM or functions and are easily searchable using BAQs. I use them for all sorts now.
Many thanks,
Nathan