Originally Posted by
Kaasschaaf
You can access the AM reservation by entering your ticket number in the KLM app or website and select your seats without any problems
No you can't - it seems to be a problem with an AeroMexico flight number that has no seatmap assigned. Have had this happen two times. Only platinum line could solve it by changing the AM flight number in the booking to the KL flight number. It's a general problem with codeshare flight numbers across all airlines.
you can access the reservation on the KLM website or app - but seat selection leads to an "not available" error.