Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Silicon Labs/Series1/BGM1/BGM121N256V2/TIMER1/DTLOCK#0x0
LOCKKEY=UNLOCKED
DTI Configuration Lock Register
DTI Lock Key
0 (UNLOCKED): undefined
1 (LOCKED): undefined
https://github.com/cmsis-svd/cmsis-svd-data