Lightbox activation link issue

Hello, I like this plugin and I’m considering buying the pro version. But, before I do that, I need to know if this little bug can be fixed.

When I use the “lightbox activation link”, the pdf opens just fine but when i close it, the layer with the PDF closes but there’s another layer underneath with a loading circle. I then need to click out of the white box to close it completely. Please see screenshot:
https://image.ibb.co/gJqChp/screenshot2018_08_29_00_33_02.png

This does not happen with thumbnail and lightbox.

Is there something that can be done to fix this?

Thank you.