Images disappearing.

Sounds like a javascript conflict. I just looked at the source code for your site. There is inline javascript all over the place, so whatever is producing it (it could be your theme), isn’t following best practices. Try switching to the default TwentySixteen theme, activate Sell Media, and if everything works, then you know it’s a problem with your theme. If the problem persists, then deactivate each plugin one by one until the problem goes away. Take note of the problematic plugin and then email the author about the issue.