Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32l4/STM32L412/LPTIM1/CFGR2#0x0
configuration register 2
LPTIM input 1 selection
LPTIM input 2 selection
https://github.com/modm-io/cmsis-svd-stm32