Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32f3/STM32F301/ADC/OFR1#0x0
ADC offset register1
Data offset 1 for the channel programmed into bits OFFSET1_CH
Channel selection for the Data offset 1
Offset1 Enable
https://github.com/modm-io/cmsis-svd-stm32