I have an STM32H745I-disco board. I created a TouchGFX project for it (with some simple graphical objects). Then I imported it to CubeIDE. At first, the project could be built without error. But after enabling an ADC module I got a linker error undefined reference to `HAL_ADC_Init'.
Unfortunately I can't help much with your issue, it's more related to STM32CubeMX and STM32CubeIDE. I invite you to add more tags (like ADC, STM32H745I-disco or STM32CubeMX), to your post to make it more visible and hopefully someone on the community can help on that.
By the way, have you tried to see examples using ADC ? When you download STM32CubeMX, you've been given multiple examples of board usage. For your STM32H745I-disco board, I think you can found them at the path :
I don't have any problem using ADCs, I mean I can use them in a usual project. But, as I said enabling ADC when the project is generated by TouchGFX Designer causes some errors.