The platformio documentation and json defines incorrectly identify the adafruit monster m4sk's microcontroller as an SAMD51J19A when it is in fact an SAMD51G19 leading to build failures in libraries like the Adafruit ZeroTimer library.
Changing the adafruit_monster_m4sk.json to use the define -DSAMD51G19A instead of -DSAMD51J19A fixes this for me.
The platformio documentation and json defines incorrectly identify the adafruit monster m4sk's microcontroller as an SAMD51J19A when it is in fact an SAMD51G19 leading to build failures in libraries like the Adafruit ZeroTimer library. Changing the
adafruit_monster_m4sk.json
to use the define -DSAMD51G19A instead of -DSAMD51J19A fixes this for me.