Can't add image?

I installed the pro version and love it! Worked beautifully, then all of a sudden, I’m not able to add new images anymore. I can change the images in backgrounds already created but when i try to upload a new one, the default WP placeholder remains and the new image isn’t saved.

I’m using event espresso, as e-commerce and other basics like per page plugins and contact form 7. Are there any conflicts I should be looking for?

https://www.ads-software.com/plugins/simple-full-screen-background-image/