93sugar

I was told by support from the company I bought my UM3 that Ninjaflex isn't compatible with the UM3. But I don't think that necessarily means that it won't work with the proper settings. I tried with similar settings that you posted and my print failed as well. The feeder ground the Ninjaflex filament and I had to open the feeder up to remove the filament. I wonder if the flow rate is set lower would make a difference. Probably even using a larger nozzle. Maybe flow rate at 80% and using a .8mm nozzle. I just got my UM3 cleaned up and back together so I'm hesitant to try it again right now.