Cannot print single filament - Always "loads" filament 1 (even when told to use different slot) then never extrudes.  

Cannot print single filament - Always "loads" filament 1 (even when told to use different slot) then never extrudes.

I just finished setting up my MMU2s on my i3 MK3S (remote controlled with an octopi, everything running the most recent versions), I had a semi-successful print of of a clown fish (FINDA sensor was having issues with one filament, so I cancelled the job and got it adjusted and it seems fine now)

But as I'm trying to print some parts for the buffer and input, specifically these: 

• https://www.thingiverse.com/thing:3233579
• https://www.thingiverse.com/thing:3545935

I cannot get it to print in single color mode. I have tried both the standard i3 MK3S and the MMU2S single profiles here: https://imgur.com/0F6v9gz (only difference between base and -octopi is the octoprint settings)

In the case of the MMU2S Single it asked me which filament to use when I started (as expected) I selected slot 2 since it was the color I wanted and the following sequence of events occurred:

1. Bed and Hot-end heated to temp
2. homing and mesh bed levelling
3. MMU2S moved to select slot 2
4. Loaded slot 2 down to hot end
5. Printed the purge/pressure line outside the normal print area (as usual)
6. moved to start point of print
7. Retracted filament from hot end and into buffer
8. moved to slot 1
9. loaded slot 1 down into hotend
10. proceeded to follow the path of the GCode without actually extruding anything. (watched for several minutes)

Using the standard i3 MK3S the only difference is that I told the printer to "Load to hot-end" slot 2, it did the normal thing of purging and asking if the color was ok. I sent the print from Octopi and the sequence of events from point 5 above, in this case I double checked the extruder motor, and it was stationary, so not even attempting to load filament to the extruder.