Ad pop ups randomly but not in app or browser based cannot find offending process

[Android Central Question]

I have an ad ad that pops up randomly full screen when i take my phone out of sleep or press power to wake it up. It either shows a still ad or a video ad and the only way to stop the video ad is to press the app button to switch it off or press x when the ad counts down VERY annoying i did catch a screen grab as there is no way else to describe it. Ran multiple security scans malware bytes and Play Store check and nothing. It shows a megaphone over the "app" when I click on running apps. I have a screen grab but seems like no way to attach it here.

 

[B. Diddy]

Welcome to Android Central! See this guide: Full screen ads. How to find the culprit. - Android Forums at AndroidCentral.com