MMU3 print constantly thinks it has run out of fillment  

MMU3 print constantly thinks it has run out of fillment

I've been trying to do an MMU3 print, and I keep running into an issue.

1. It keeps retracting the filament when there is no need - I believe it thinks it has reached the end of the filament - which it has not.

2. When it does said retraction, it retracts a small amount, leaving most of the filament in the PTFE tube between the MMU3 and nextruder

3. It then moves the selector head to the next filament position, and proceeds to push forward a bit (about an inch) of the filament I had been using

4. This causes the filament to now be jammed, as most of it is still in the PTFE tube, the head has moved, so I now have a small loop of filament coming out of the rest of the MMU3 body, looping in open air to the back of the selector, and then into the PFTE tube.

5. I have to manually cut the filament before the selector head, and then move the selector head past the 5th filament position, so that it's not jammed and I can pull the filament out (both the loop that was created when it 'ejected' the filament, and the filament stuck down the PFTE tube).

The problem is, I have a lot of filament left.  It was printing fine, until it decided I had run out or something and therefore needed to change the filament.

What could be causing this?  I am assuming some kind of filament sensor that is just plain mistaken?

Why is it not retracting the filament the entire way until the FINDA can no longer detect it (ie. it retracts it only a tiny way)?

Is it possible my FINDA is flakey or too far away (it should not be, it detects the filament just fine to push it to the nozzle)? or what?

I cannot do a single MMU3 print right now due to this issue.

Preston