Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32u5/STM32U535/TIM1/ECR#0x0
encoder control register
Index enable
Index direction
First index
Index positioning
Pulse width
Pulse width prescaler
https://github.com/modm-io/cmsis-svd-stm32