I salute web developers. Finding a problem is like trying to debug a program that's spread out across 5 dimensions. In machine language.
Troubleshooting for web is a lot of trial and error mixed with guess work. In this case, I saw your htacess/SSL comment and I fiddled around with the image URL based on that info.
URL rewriting always causes issues, no matter how certain you are that it's been done correctly. I've worked in htaccess because no one else wanted to or knew how. I didn't either, but I was good at breaking things and reverting back quickly.