Android app HTTP image links not working when connected via HTTPS

I have a problem when connecting to openHAB 3 UI over HTTPS in the Android app.
All my HTTP links to pictures of my floorplan and also some other HTTP image links won’t resolve in the app when using HTTPS. In the normal HTTP mode everything works just fine and on the desktop browser also everything is working just fine. When I access openHAB on desktop with HTTPS the images do resolve though.
Is this a bug or did I just flip the wrong switch?

Several browsers, including Chrome and thus probably WebView as well, are blocking mixed content (http elements on https websites).
Can you change all links to https?