Why does the green phone answer button disappear

[Android Central Question]

My phone rings, I can't get to it quick enough. It rings again but all green answer buttons are gone. Then I can't take any call until all people quit calling so I can call them back. How do I work around this problem?

 

[B. Diddy]

Welcome to Android Central! Which phone? Is this when you get a call while actively using the phone for other things, or when the phone is asleep? If you're using the phone already for other things and you get a call, do you get a notification for an incoming call at the top of the screen? If you get a call when the phone is asleep, do you get the main incoming call screen?