I've reproduced the problem on your site. I see that the picture form cleans while other fields remain filled out and no entry is submitted. After investigating the problem, I've found the reason. See what's happening on Cassiopeia template:
https://postimg.cc/MvWQcYcN
"The maximum number of entries for this contest has been reached".
You need to increase number of entries (in global options or in contest settings). See documentation.
The second step is: your template does not display Joomla alert messages. And that's why a user sees nothing during entry submission.
I've checked out and this problem is confirmed. Just try to use incorrect credentials when you log in to your site on the front-end.
There should be default Joomla alert message informing about incorrect credentials. But this alert is not displaying.
Please contact Gantry developers to resolve this issue.
And a little recommendation: you can install Spanish translation of NorrCompetition. It is not 100% completed but anyway, it helps.
Please let me know about your progress.
Regards,
Eugene