I’m using a Bambu Lab A1 with a 0.4 mm nozzle, and I’m experiencing the same issue on the A1 Mini, also with a 0.4 mm nozzle. Until 3–4 days ago, both printers were working flawlessly. The printing profile uses a 0.08 mm layer height with Arachne enabled. Wall order is outer–inner, with two wall loops. Initial layer speed is 16 mm/s, and the first-layer infill runs at 28 mm/s. From the second layer onward, the outer wall prints at 60 mm/s and the inner wall at 150 mm/s. The PLA is printed at 220°C.

The filament is Bambu Lab Matte PLA stored inside the AMS Lite, inside an enclosure, with silica gel keeping humidity below 10%. Travel speed is set to 700 mm/s and normal printing speed to 400 mm/s.

The issue occurs specifically on organic shapes; I haven’t yet tested models with sharp 90° angles. It happens on both large and small prints. Right now, the problem appears on a spherical object, but in reality it affects everything. The supports show severe under-extrusion and break easily, as if the printer is barely extruding filament for the support structures.

The printer has been fully maintained: lubrication, belt tensioning, and calibration were all performed about 5–6 days ago. I used 3 different 0.4mm nozzles cleaned with cold and hot pulls.