My patients can't see me

When I open doxy, everything looks normal except my preview screen box is just black. My patients only see a black screen too. They can hear me and I can see and hear them. I’ve checked the settings and camera. All fine there. I tried logging out and back in plus restarting my computer but no help.
I need help with this ASAP.
Thank you!
JP

2020-06-16T04:00:00Z