Certificates are not visible or printable for some of the students. They can see and print only the upper half. On my computer shows well; again, I have to make a copy and email to them, which defines the entire purpose of having automatic issued certificates. I Can see that on an ipad, the certificate does not show correctly either. This is an issue that appeared after one of your updates and I suspect it has to do with the operating system each student is using; however, it should not be a requirement to use only certain OS to be able to access certificates or any other access to the courses.
I checked the template you created - I don't see the logo - it shows when you click to open the certificate, but once it loaded (when you see the printer / pdf icons on the tope right) the background log disappears. See attached for reference.
Okay i found that in your certificate template there is some related posts appearing form a third party plugin :
http://prntscr.com/c14otp
Please try disabling it and try again .
NO - This is especially an issue for MAC users.
Have you tried to disable the "Related posts" in your site which is also appearing in the Certificate for the user and this making the certificate distorted in popup.
I don't see a "related post" plugin. anywhere else to look to disable?
This is coming from Jetpack.
Try disabling related posts from Jetpack. Let us know if this helps.
For now problem solve. I had to disable jetpack completely and it seems to work. Just disabling related post did not work.
Does this theme need jetpack?
I checked your site and found the Jetpack to be activated but the related posts disabled and certificate is working fine check :
http://prntscr.com/c4u8lo