Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Silicon Labs/Series1/EFR32FG12P/EFR32FG12P431F1024GM48/WTIMER0/TOPB#0x0
Counter Top Value Buffer Register
Counter Top Value Buffer
https://github.com/cmsis-svd/cmsis-svd-data