I had skipped initial deboarding and started with catering, then went to boarding, FWIW.
I had same problem, but after boarding. boarding finished, the front baggage loader on the NGX backed away, but didn't leave, the aft one remained, and then the GSX screen said boarding completed, waiting for baggage UNloading.
interesting, I hope it fixes another problem I just found also. When I call the catering truck on the CLS-MD81, both belt loaders drive to the plane, the bagagge trucks pass the loaders without holding and drive away and then the catering truck appears. The belt loaders never leave the plane anymore afterwards.and this not only happens with the MD-81 but with severall other planes also