I am having the same issue, after restart the rear camera works fine but once I flip it for selfie mode, it hangs and doesn't work. Then the camera app just goes black and no other application can access the camera too.
Even I started facing this issue on 2nd March after installing the update. The camera randomly stopped working. I never had to restart my phone due to camera problems, there were none, other then the usual cannot flip, it always worked after retracting.
I took the SMMI test and it failed. Now today, I factory reset my phone and it still doesn't work.
Have you been able to fix it in your Your phone Rupesh?