"Please try after some time" – but no errors

Dear Support,

I’m using the latest version of the plugin and WordPress on a production site, with the single opt-in option. When hitting the subscribe button, an error message displays:

“Please try after some time.”

However, the user gets subscribed to the list. I already tried uncommenting the two lines in the .js files, but no luck, and no additional information.

Temporarily, I have translated the error message to “Köszönjük, hogy részt veszel a játékunkban!” using Loco Translate, since this is a production site, and users should not see error messages.

You can check out the page on which the plugin is loaded here.

Please advise!

Thank you in advance.

https://wordpress.org/plugins/email-subscribers/