@Historylover 

I have the Oppo Reno Z.

I know the issue you have. For me it just changes every now and then?? I just tried calling myself from the home phone. Got the usual big green button to swipe.

I Think when you get the two icons you just need to Tap/press the small green one? God knows why it changes!

I installed the latest update yesterday, so that might be part of the problem, but it Was happening before that anyway