I have had the same issue with Oppo products. The Oppo customer support told me that they are out of ideas. Everytime they fix something Apple comes along with a new firmware that causes new issues.
I talked to Apple (1hr on the phone + 20 mins genius bar). They said that it is an issue of the 3rd party manufacturer and I should only use Apple products. I showed them the MFi label. Then they told me to wait for iOS11.
I decided to move away from Apple after 10 years.
Please don't blame 3rd party/MFi products for this. It is 100% Apples fault.
When Steve Jobs died, Apple died too. It's sad but true.