UMO bed does not lower every time after print

[zumfab 3]

For the most part, my prints end up of pretty decent quality and the bed usually lowers after each print. Exactly how you would want it. Occasionally, it does not lower after the print, leaving the hot extruder in contact with the finished print. As you can imagine, this ruins an otherwise fair finish. Of course it typically happens with long prints, though it happens with shorter prints too.

Some Google Fu does not tell me what happens and how I can fix it. Do you guys have any idea? It is not game breaking, but it is becoming somewhat annoying. If I could prevent it, that would be great.

 

[gr5 2,167]

This is very common when printing through USB. Do you print through USB? Or with an SD card?

 

[zumfab 3]

This is very common when printing through USB. Do you print through USB? Or with an SD card?

 

The former. I print via USB. I have a lot of small changes to make to my models, using an SD card would be quite a hassle.

 

[zumfab 3]

Any ideas on how to prevent this while printing over USB? I try to lower the bed manually, but that is not always effective or convenient.

 

[zumfab 3]

This is weird. Today I printed a long print via a controller and I got the same result. Luckily I was standing right next to it, so I could prevent major damage, but there still is a dimple visible. I also noticed it did not quite finish the last layer. A small patch of about 1 centimeter square was left unprinted.

This is all quite odd, as the three hour print did not cause any trouble. Any ideas on how to fix this?

Update: this is very strange. Looking at the G-code, the troubled print just seems to end:

 

G0 F9000 X84.83 Y104.86
G1 F3000 X80.10 Y100.14 E3013.96344
G0 F9000 X79.54 Y100.14
G1 F3000 X84.26 Y104.86 E3014.00523
G0 F9000 X83.70 Y104.86
G1

While the correctly printing file has a footer:

 

G1 F3000 X32.06 Y42.14 E116.01087
G0 F9000 X32.34 Y41.30
G1 F3000 X34.82 Y38.82 E116.03279
M107
G1 F2400 E111.53279
G0 F9000 X34.82 Y38.82 Z13.15
;End GCode
M104 S0                     ;extruder heater off
M140 S0                     ;heated bed heater off (if you have it)
G91                                    ;relative positioning
G1 E-1 F300                            ;retract the filament a bit before lifting the nozzle, to release some of the pressure
G1 Z+0.5 E-5 X-20 Y-20 F9000 ;move Z up a bit and retract filament even more
G28 X0 Y0                              ;move X/Y to min endstops, so the head is out of the way
M84                         ;steppers off
G90                         ;absolute positioning
;CURA_PROFILE_STRING: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

I reexported the same file, and now a header appears. It seems Cura simply does not supply the full file at times. Is this a known problem?