@kisvegabor Since the RT1064 is part of the ratified hardware for LVGL it would be helpful to publish which version of LVGL the hardware was tested with. I can only assume this board was tested with V7 since V8 would surely have exhibited the problems that I describe above.
Publishing a benchmark along with LVGL certified hardware would be helpful (as suggested in this post) to many who are reviewing the library and still in the process of choosing hardware.
It also substantiates the operation of LVGL on the target platform and may well assist in debugging across different versions of LVGL (as I have encountered). Still no resolution to this BTW so I am having to stick with V7.