I used the free version, but after a while I upgraded to the paid version.
（ARI Stream Quiz - Personal v. 1.5.45）

However, after upgrading, when I try to create a new issue, the screen keeps loading and I can't create the quiz.

I cannot delete the quiz created in the free version.

I'm having a similar problem with this thread
www.ari-soft.com/ARI-Stream-Quiz/61865-Quizzes-not-loading.html?_2020051003

I would like to use the paid version, so please tell me how to fix it.

Hello,

It looks like a problem with a 3rd party plugin or admin theme. Could you provide a temporary access to your WordPress backend by email so we can investigate the problem?

Regards,
ARI Soft

After clearing the browser cache and restarting, the error was fixed.

It was an error caused by my simple mistake.
I can also create new quizzes.

Thank you for your reply.