Solution for me: in newest twrp 3.1.1-1 unoffical, there in the install settings screen is an option to choose "legacy zip". Aktivate it and zip will install without errors
Tried to flash the zip today, but twrp gives me an error message saying "this is for moto z play addison. Your phone is.. "
Well, I'm on addison with patched decrypted stock 7.1.1. and have no clue...