After Photoshop crashes or otherwise abnormally exits, artboards display incorrectly. Artboards may redraw incorrectly even if Photoshop has not crashed.
Artboards are optimized for RGB mode and advanced GPU mode.
If the graphics processor option is set to Basic or turned off; if your graphics card is unsupported or it doesn't support the advanced drawing option; or if the graphics driver is outdated, artboards might redraw incorrectly. If Photoshop has abnormally exited, it might reset your graphics processor drawing mode to Basic.
Although it's not mandatory to restart Photoshop after changing the Drawing Mode or any graphics processor settings, we highly recommend that you do so.