STM32H735G-DK with HSI clock source

[RReta.1]

Hello,

I am trying to reconfigure my STM32H735G-DK to use HSI instead of HSE for a TouchGFX based application.

The Default config (at a high level):

HSE Source, main CPU at 550 MHz and peripheral bus at 275 MHz or 137.5 MHz; OSPI at 200 MHz and LTDC at 9.6 MHz

The HSE custom clocked (this worked):

HSE Source, main CPU at 400 MHz and peripheral bus at 200 MHz or 100 MHz; OSPI at 192 MHz and LTDC at 10 MHz

Next I replicated the same clock output as the HSE custom setup, but using HSI as input.

This time the code build okay, but each time I flashed, all I got is a blank screen on the LCD.

Is there any limitation where the clock has to be HSE to use with LCD/TouchGFX or am I missing something?

Thank you for everyone's time