For all who are experiencing this issue, upgrading to the latest version of STM32CubeIDE (1.5.0) successfully resolved my issue. I was previously using 1.3.0. I presume this error was caused by some issue in the CubeMX-generated initialization code.

By manually calling __HAL_RCC_USART1_CLK_ENABLE(), I can see that USART1 CR1 is now changing to the expected value (one would not think this step necessary, as this happens in HAL_UART_MspInit as generated by CubeMx prior to any configuration being a...

I am encountering the same error; all other UARTs are working, using Nucleo-L4R5ZI. USART1 CR1 remains at 0, even after the MODIFY_REG instruction is issued during initialization. I suspect that this has something to do with USART1 being on APB2 whil...