Can't swipe down or hit the lower buttons

No, when I'm on a call. It's like everything locks up and becomes just a phone only. Can't hit any buttons (except the keypad for the in call) or swipe down for notifications.
 
No, when I'm on a call. It's like everything locks up and becomes just a phone only. Can't hit any buttons (except the keypad for the in call) or swipe down for notifications.
So your in the phone , does it automatically answer ?
 
No I can answer. It only starts locking up after I answer the call or before I answer like when I get the notification that someone is calling (like to answer or reject).
When someone calls does the whole screen show just the call ?
 
Do a factory reset? If it were my phone behaving like that I'd factory reset and see how things go.
 
Any Accessibility features turned on in Settings>Accessibility​?