Not able to start an AMS print on P1P from sd card

Hi everyone,

I wanted to start a multicolor print on my P1P with AMS from sdcard. However I am not able to start the print. When there is no filament in the printhead (but 3 rolls in my AMS) I get an error message that there is no filament in the printer. So I tried loading some filament from AMS via BambuHandy, which works, but when starting the print the printer complains that there is stil some filament in the printhead and I have to unload it first.
Anyone else having this issue? What am I missing? When sending a print directly from BS there is an “enable AMS” option, this option does not appear when you export the sliced file. The same file prints perfect when sent directly from BS.