Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Silicon Labs/Series0/EZR32HG/EZR32HG220F32R55/MSC/MASSLOCK#0x0
LOCKKEY=UNLOCKED
Mass Erase Lock Register
Mass Erase Lock
0 (UNLOCKED): Mass erase unlocked.
1 (LOCKED): Mass erase locked.
https://github.com/cmsis-svd/cmsis-svd-data