Same issue just started this morning
I just started experiencing the same issue with the "duo camera blocked" message. I removed the case and cleaned the lens, no difference. I had read before of apps interfering with normal camera functionality and was about to uninstall recently installed apps. Before doing so, I went back to the camera to try it again. In the process I accidentally switched to video mode. When I switched back to regular camera mode the problem resolved! Try switching to video mode, then switch back to standard camera!