Problem with support structures  

RE: Problem with support structures

first layer looks good - even though you are printing PLA on the textured  sheet (hard to do).  Without a sliced .3mf file (save project from Prusa Slicer) it will be hard to diagnose in detail.  However, it does look like you are running possibly too low on your first layer Z since the second layer is dragging the nozzle (that's what causes the blobbing, I think)

RE: Problem with support structures

I'd try to print without the MMU2 to check wether it's the MMU or the extruder causing the problem.

You can do this by just removing the PTFE tube between selector and extruder and then load from an empty slot. At the start of the loading sequence just put a short bit of filament into the selector (to trigger FINDA) and then after two seconds or so feed the filament  directly into the extruder. Your printer and MMU will think everything is as usual and start the print. (You can also do that with "Load to nozzle" from the LCD menu and then use GCODE sliced for an normal (non-MMU) MK3 printer...)

If you still have the same problems it's not the MMU, might be caused by the changes of the extruder when upgrading to MMU, might be one of the usual suspects (First layer calibration, bed cleaning, heat creep due to enclosure..) but at least you ruled out your new MMU. If the problem is gone, it's probably a friction related problem in the MMU's filament path.

RE: Problem with support structures

PS. If you use original Prusament the default settings in Prusa Slicer are perfect, no need to play around with them, the problem must be something else. The use of default settings makes troubleshooting way easier...