High Priority freertos task stops running a soon as touchgfx starts

[CHech.1]

Hi,

I've encountered a strange problem.

I have two High Priority tasks and the touchGFX task set to Normal Priority.

Both High priority tasks are wakeup, check if a variable and go to sleep with osDelay(10).

The tasks do not return from osDelay after a touchgfx gui starts..

Any ideas what might cause this?

thank you