We have just updated both wordpress and all plugins and wplms to the latest versions and our check results no longer shows anything to the user (though it appears to retrieve some content).
I can give access to our staging site if necessary.
WP version: 5.2.2
wplms - 3.9.3.1
I don't know if this is the right fix but it worked for me:
In includes/js/course.js there are 2 event listeners added for $('.quiz_results_popup').magnificPopup({.....
Commenting out the one on line 347, leaving only the one on line 754 fixed the issue for me.
MkModerator
Well we are not able to replicate the issue at our end .
Can you please share your site url and admin credentials in private reply to check this up at your end .