It looks like this issue was discussed previously:
But was conflated with an issue regarding the order that that tanks were being drained in:
Perhaps this will still be rejected as a "feature not a bug" but it would be really nice if there were a way to isolate monoprop to individual stages.
- Create a rocket with two monoprop tanks separated by a interstage.
- Attach an RCS nozzle to each tank
- Activate only one of the RCS nozzels and fire it until the first fuel tank runs out
Unless there is a fuel line or fuel transfer enabled on the interstage then RCS attached to one stage should not draw monoprop from tanks in another stage.