I started a print late last night that was going to take about 8 hours to complete and woke up to a filament mess. I cleaned the mess thinking it was just a failed print and found this had happened.
My guess is that at some point last night the head may have pressed down on the filament or dragged it and then pressed down. Now there is a ton of filament inside with part of the plastic bubbling up from the head melting. I ended up with a bunch of this as my print model.
Was supposed to be this…
(Flux 0.2.11 x64 w/ fw b15)