I have 2 sets of A7( 2016) which both have the same problem on main camera. The camera will just black out when launched the built-in camera apps, but can switch to rear camera which working normally. The only solution is power cycle the A7( 2016) then the main camera becomes normal.
The Quick Charge feature in the A7( 2016) is not the QC 2.0 standard. I’ve tried vary brands of AC adapter and external battery which support QC 2.0 which the A7( 2016) just at normal charging. so it camera is slow and charging is normal thanks .