"apk time recommend" pop-ups

[Wah G]

My android v. 5.1 keeps getting pop-up ads entitled "apk time recommend". [see pic of an example, below]. I cannot get rid of them. I cannot even find mention of "apk time recommend" on google.

I have looked in my Apps list and have been pretty liberal at uninstalling downloaded apps. I have factory reset my phone. This seemed to stop the problem for a few days. I've installed and run several virus and ad blocker apps, all of which report my phone is fine, but have no effect on the pop-ups.

Does anyone know what this is, and more importantly, how to get rid of it? Thank you.

 

[El Presidente]

Have you installed anything outwith any legit (Google Play, Amazon etc) app store?

Try clearing the cache and data on whatever browser you use.

Do you have any Go apps installed (Go messages, Go Launcher etc)?

 

[Wah G]

Thanks El Presidente,
I've not installed any apps from unknown sources. I don't have any Go apps as far as I can tell.
I use Buzz Launcher and have now cleared its data and cache. Unfort. all that did was reset the launcher, thereby removing all my personslisations.
But an hour later an "apk time recommend" add popped up. :-(