I loaded version 18.11.1 to my UM2 ext+ today and started a routine print. In the middle of the job, it stopped, feeder pulled the filament completely out (exactly like when you want to change material), then after a few seconds printer continued printing with no filament of course! I paused it and fed the material back in manually and continued. Is this a bug or am I doing something wrong?! It seems very strange.