I am puzzled with the problem I try to solve for a week now
I have display st7796 with ft6336 touch and code that works nice with lvgl8.3.6 but not with any newer version
I tried with 8.4 8.11 and 9.2.2 and code compiles ok after some changes but widgets are not responding
Touch input is working I see printed coordinates on serial monitor
Please add prints after lv_timer_handler and into your flush_cb to see if they are called.