Following the big GDPR push I have converted sites to use https via asp.net code EG;
If Not Request.IsSecureConnection Then
Piece of cake!
But images seem to show as insecure content and browsers do not show the desired padlock.
Running the Firefox web console I see that the offending item is the RadRotor image urls which are not shown in https format and thus provoke the insecure/mixed content warnings. I guess this could be fixed by using the full absolute url but then the development version and the public version would be different, which sucks.
There has to be way round this without using absolute urls rather than relative ones (eg ImageUrl="~/images/image1.png")