Air printing/jamming midway through raft creation
Your symptom sounds like heat creep might be stopping the extrusion.  See if this discussion helps you troubleshoot: Understanding all the ways to avoid heat creep
Note: decreasing speed and increasing temperature makes heat creep worse.
Your picture of filament shows what people with Bowden extruders describe as typical of heat creep.  The Bowden tube isolates the filament drive motor from the temperature of the extruder.  On well put together Bowden tube extruder, there is no place for softened filament to bunch up. So, heat creep occurs when the melted filament goes up the region of the heat break in the heat sink.  Thus, to determine heat creep one needs to ask, &quot;Is the expanded part of the filament extending into the heatsink.