We are currently on Forms 10.3.1 and have published one form externally through DMZ server, the form is insecure due to mixed content. According to the console log, the logo generated by the form's theme is causing the issue. This logo has been uploaded through the form's Themes page by dropping the image file. When I copy the logo link and change it to https, it works fine; however, the auto-generated logo link is using http.  

The message looks following:

Mixed Content: The page at 'http://(public domain)/forms/(form name)' was loaded over HTTPS, but requested an insecure image 'http://(public  domain)/Forms/Handler/FileRouter.ashx?guid=ba4db77f-8d10-4f73-fb8f-3fO744682ceb'. This content should also be served over HTTPS.

I wonder if there is another way of uploading the logo image file or if this is a known issue. 

Thanks,

Olivia