Some filaments such as abrasive, very soft ones or rolls that are too big or small are not compatible with the Bambu AMS filament changer. The abrasive filaments wear down parts and the TPU is too soft and bunches up in the long tubes. The AMS unit itself doesnt fit most 250/500g filament spools and larger diameter or width ones also wont fit. The easy solution to this is a y adapter that allows you to feed in filament to the toolhead without using the AMS.
Here is the Y-Splitter I printed out on Printables. It does need 3 PC4-M10 as well as magnets that you will need to purchase separately.
This worked out very well for me. Using Bambu Handy or Bambu Studio to heat the nozzle and unload the filament like I used to on my Ender3 was a bit weird instead of having the AMS handle everything but this will allow me to print with more variety than I normally would be able to.