hello. This may be caused by rendering that 1. What system are you using? 2. what is your graphics card? 3. If it is Windows, please check and update your drivers. 4. Please open the graphics card in the settings screen of the drop-down list Compatible mode
ok I have found the issue. it seems the Chitubox does not support my current screen resolution. i moved the program to a second screen with lower resolution and refresh rate and its working fine now