Was going to print a skull for halloween and as per usual i just chose the filament i wanted. To be completely clear i had a regular PLA Black loaded and then loaded a PLA with glitter to print the skull with…and to my surprise, the AMS picked the regular black and started printing.
As i felt it didn’t matter if the first layer was just black, i paused the print and used Bambu studio to just change the filament, which just didn’t work.
The only thing that happened was that both slots blinked at the same time, which i never experienced before, so now i reprint it from scratch.
I even removed the regular black from the AMS so it wouldn’t get confused again. 
Is this something that happened with the last update?
(As i’m proofreading it for mistakes, i felt i had to add one thing: i ofc have no proof of this. I ofc could have chosen the wrong AMS slot, but since i was aware of the other black, i really don’t think so. Hopefully i’m not going crazy and Bambu Labs answer that they are aware of the issue and will release a quickfix as soon as.)