The door interlock is a feature which is in place for the Nomads which are sold in Europe (we may also offer this as an option for schools here in the States).
I believe it’s supposed to also be supported by a special firmware — suspect it’s a software glitch in CM where a variable or setting got toggled somehow.
Please check your Grbl settings and CM preferences and send them in to beta@carbide3d.com and they should be able to sort you out — might want to go ahead and go back to CM3 and Grbl 0.9: GRBL 1.1 and Carbide Motion 4