Same issue here. Happens throughout each print. Disconnecting and reconnecting. If it happens at the end of a print, the printer thinks there is filament in the external spool and the ams will not cut and unload. Turning off/on the printer seems to reconnect and then the ams can cut and unload. Of course this would prevent a muli-material print which defeats the purpose of the ams. I’ve submitted a ticket. We’ll see what happens.
I have read that replacing the small AMS interface board on the back of the printer fixes this issue in some cases. This can be purchased on the Bambu website for around $10. The installation processes looks like a hassle but I might give that a try.