Hi,
when deboarding is in progress, pax already deboarded but cargo deboarding is still ongoing and you call for boarding cargo will finish deboarding (thats fine...), they docking off and moving back -> Cargo dont come back to start their boarding progress. They remain "idle" on the side; pax were boarded... Boarding phase cant be finished.
You can say it's no meant to call for boarding while deboarding is still in progress, but you allow kind of service queue in other situations (like Boarding is in progress and you call for pb it waits until boarding is finishes).