Hi,
First, thanks for the plugin! I just installed it and it seems to be working well except for 2 issues:
First issue is when a user registers and they get the email to verify their email address and click the verify link, it goes to the website correctly, but just displays a white box with a check box inside, but there is no text to say they successfully verified, and there is no way to close this box. Users have to close the the entire browser tab and then go back to the website again.
Second problem is in the WordPress admin when I click the \"Mark as Verified\" to manually verify a user, it does not change their status to Verified.
Regards,
Chuck

Welcome to our forum.
popup box issue might happening if your page contain any js error, please check browser console area to see is there any js error is showing, please send me a screenshot of browser console area.
i have checked "mark as verified" its woks fine here
https://imgur.com/KbquuS8
Could you please send me a video walkthrough to regenerate errors.
Latest version of User Verification plugin does not allow admins to login to the backend. I had to deactivate the plugin just to be able to login.