Check the diameter of your filament, and you may find you have a bad batch of it. I have been having very frustrating under-extrusion problems with the Bambu 95A HF TPU on an X1C, after a few prints that came out fine. In the past two days it has progressed to the point that I can’t even get it to load properly. Finally this morning I used a precision caliper to measure the diameter of the TPU. Instead of 1.75 mm ± 0.03, it measures only 1.14 mm. No wonder the extruder can’t grab it reliably. Just to double check, I measured some PLA with the same calipers and it came out almost exactly at 1.75 mm. I should add that my TPU has undergone at least 24 hours of drying, and it has been either in the dryer or vacuum packed with dessicant ever since it arrived. I’m going to ask Bambu to send me a new refill of the stuff.