Dual extruder print on Dreamer sticking to nozzle

Confused as hell on this one. I've been printing polyhedral dice the past couple days; the 12-sided and 20-sided are about 25mm diameter. Each has printed fine two or three times. Right extruder prints the die body, left extruder prints the numbers.

This afternoon I came in to find that one die had printed a bit more than halfway, then become hung up on the right extruder, resulting in a big glob o' plastic. Figured maybe the bed had just lost level, so I leveled it and started re-printing.

Same thing happened the second time. So, I tried printing the 12-sided die that had printed successfully earlier. Same thing happened with that one.

I made a simple, 30mm tall cylinder in OpenSCAD using only the right extruder. Stared at it while it printed...perfectly successful.

Any thoughts on where I need to troubleshoot next?