I have had this problem 3 times in recent prints having behaved flawlessly across 50 prints during my first month of printing.
Twice on the same 4.5hr single colour print, the job cancelled unexpectedly as described. It did not stop in the same place each time and there was nothing notable happening at the point of stopping.
Machine: P1S + AMS
Stock SD card: No
Bambu Lab Slicer Version: Bambu Studio 1.10.1.50
P1 Firmware version: 01.07.00.00
Approximate layer number where it failed: very roughly 30/125 first time, 20/125 second time
Approximate time elapsed between print start and failure: approx 40% ~ 2 hours in first time, approx 20% ~ 1 hour in second time
Today I decided to down version back to 01.06.01.02 and the first print worked fine, however the second print has just experienced the exact same problem again.
Machine: P1S + AMS
Stock SD card: No
Bambu Lab Slicer Version: Bambu Studio 1.10.1.50
P1 Firmware version: 01.06.01.02
Approximate layer number where it failed: approx 60/125
Approximate time elapsed between print start and failure: approx 2 hours
So frustrating as you simply don’t know whether a job is going to work or waste filament. Please keep updates from the logged tickets coming as you get them as I am feeling paralysed by this now after such an amazing introduction to this hobby,.