Lock screen appear while incoming call

[RajuAvery]

I had some strange issue in my Note 9 phone, all of a sudden my incoming call screen wont show. Only I can hear ring tone sound then I have to unlock my phone to answer the call. Can any one help me to solve this issue. 

[suniljaiswal]

I had some strange issue in my J7max phone, all of a sudden my incoming call screen wont show. Only I can hear ring tone sound then I have to unlock my phone to answer the call. Can any one help me to solve this issue.