Are you new with that machine? I suspect that you don't set the pinch rollers correctly.
In opposite to most of the print-only-machines, the print & cut-rolands do not measure the width of the media: They measure the distance between the outer pinch rollers (like a cutting plotter).
If you set media to that printer the same way as regular print-only-machines, what means leaving all the pinch rollers in position instead of setting both outer pinch rollers to the outer borders of the media (with removing some inner pinch rollers if needed), you will get permanently nearly the same width independently of the width of the media. And, in addition, it could lead to problems with long distance tracking if track the media with the wrong pinch roller on one side.
If the printer sets a value for the width of the media after scanning, the sensor and the flat cable of the tool carriage (were the sensor is mounted) are ok (if they are damaged, you get a value of 0mm or an error message).
If you know how to set the pinch rollers on this machine, and even if set the distance between the outer rollers to around 1'200mm, 1'000mm, 700mm (and so on) without getting correct values, you need to check further, but I haven't seen something of this kind until now, and I support roland printers since more than 15 years.