I have tested all the setting and virtual background before the meeting, it work fine.
However, when I actually joining the meeting, the virtual background(1.5MB, 1920*1080, JPG) just doesn't work and Webex not allow me to add it again, I guess its because the size is too big, then I use the smaller size version (700KB, 1280*720, JPG) its work.
Does anyone experienced the same situation? I want to know why and avoid it next time.