One of the only consistent frustrations I have these days is initially feeding TPU into the single or dual extruder (but primarily the dual). The feed rate (speed) from the touchscreen in Control > Nozzle mode is a bit too fast and the TPU likes to get lost inside the extruder body. Slowing down the feed would absolutely solve this. So, similar to how we can select the increments when moving the head around, maybe some increments for feeding filament?
I use 250-254 degrees for charging TPU. Then the advance fits.
Try lightly dragging the tpu between your fingers as you insert it. It seems to help it take the right path and not get bunched up trying to find the path.
For the single extruder you can also open the feeder door and run it manually into the hole then close the feeder door.
I also opened up the single extruder’s feeder door spring so there is a little bit more pressure on the guide wheel.