I activated premium version of AVG Anti-virus on my new Xperia XZ Premium and after scan, the AVG shows one unresolved threat about having Unknown Sources enabled in my phone. Trouble is Oreo no longer has such option for Unknown Sources as it used to be, only shows certain apps like Chrome, Drive, Gmail, Malware and Messenger and all these are Off for Installing Unknown Sources.
So why AVG keeps showing me I have a problem? And how can I make it stop or how turn something off when it's already off? 
Could it be lack of AVG compatibility with Android OREO?
Hello Steve,
I understand that you have some difficulties with AVG program installed in your android phone. To best assist you with this, I suggest you to contact our AVG mobile support.
Please click on the following link ( http://avgclick.me/AVGtechnical ) and fill out your details, select platform as "Android" and the name of AVG Program that you have installed on your mobile. In the description please completely explain your issue and click on "Email" option. When filling out your details choose "Yes" to the question "Are you currently using any paid/trial AVG products?" even though you may be using the Free version. The AVG mobile team will reply to you via email with a resolution.
Hello Steve,
I understand that you have some difficulties with AVG program installed in your android phone. To best assist you with this, I suggest you to contact our AVG mobile support.
Please click on the following link ( http://avgclick.me/AVGtechnical ) and fill out your details, select platform as "Android" and the name of AVG Program that you have installed on your mobile. In the description please completely explain your issue and click on "Email" option. When filling out your details choose "Yes" to the question "Are you currently using any paid/trial AVG products?" even though you may be using the Free version. The AVG mobile team will reply to you via email with a resolution.
Hello Steve,
Our mobile team have received your request, they are processing your case. You will receive a reply from our mobile team soon.
Best regards,
Alok.