Most likely there is a conflict with your other plugin or theme.
Please try to deactivate all your plugins one by one and check the issue. Thus you will find out which plugin causes the error. If it won’t help, try to switch temporarily to a standard WordPress theme.
If it doesn’t help, then contact us through our internal support
The plugin did this on my site installation as well. Viewer was loaded, but created images do not load. Cannot reconfigure my theme or plugins just to meet the demands of your publication plugin. Not worth it for me and my client. Maybe you should compile a list of incompatible plugins or themes so developers can check it first to see if there is a conflict and judge if they want to buy the software.
As I know, we already refunded your money for purchase. Unfortunately we can’t control all WordPress developers and all plugins.
We always are trying to resolve such kind of issues, if we can. But sometimes conflicts can’t be fixed in our plugin, because wrong code is implemented in third party plugin.
I recommend you to read this developers manifest: https://supsystic.com/blog/wordpress-developers-manifest/
Supsystic programmers are always trying to make a code, that does not interfere with other developers.