Here's what I noticed. My wife bought me a lifeproof FRE case for my ip8+. The case seems to interfere with the normal operation of the phone. Audio was no issue but when using anything that involved holding the phone button and using siri, the display would go out like the sleep button was being pressed. One time it wouldn't allow me to even hang up the phone. I tried changing home button sensitivity and it didn't make a difference. I took the case off and put the otterbox defender back on and it worked with no issues.
No issue when no case being on the phone either.
I removed the Lifeproof to "exercise" the buttons and it still happens.
I used the same case on my ip7 and the only issue I had was having the clean the lens once in a while.
I like the idea of having the lens covered for protection. That allows me to carry the phone in the same pocket as change and other objects.
Looks like I'll have to send it back to Amazon and try a pelican marine or maybe HIT case.