White screen on board with TouchGFX, but runs on another board - where to check ?

Hello,

I have a strange problem and would kindly ask for some hints of more experienced users where to start checking the code...

We have TouchGFX project on custom board. We currently have only two boards (so could be HW problem). On one board GUI runs without problems, on second same board, it shows white screen.

What is interesting that more simple demo with TouchGFX works on second board, full blown GUI shows white screen, but works on first board...

Is there maybe some logical reason for this behaviour, so I can start checking?

What is you first thought?

My idea is external flash, but why would simple demo with two buttons work - beecause buttons are not stored in external flash ?

Thanks in advance,

regards,