Gateway Skeleton Theme: footer missing when viewing in https

I am using the Gateway skeleton theme. Whenever I view the site in 'https', the footer portion doesn't show. I am noticing the samething in the grav demo site as well. Here is a screenshot of what I am referring too.

Viewing in https:
http://img.photobucket.com/albums/v645/duceduc/ss/ss-01_zpsnurek3iy.jpg

Viewing in http:
http://img.photobucket.com/albums/v645/duceduc/ss/ss-02_zpsh5wr398v.jpg

I do not know if it is the ssl certificate that is causing the issue. Both Grav and I are using the same ssl certificate by Let's Encrypted.

I don't know what that bottom part is doing, as the copyright is already included before, in the dark footer.

Looks like it's used for infinite loading, in the blog? As it's called "infinite-footer".

I do not know the exact term, but as you go further down the page, a transparent layer pops up where we can click on the caret symbol to navigate back to the top as seen from the 2nd screenshot. It seems weird that it only happens when the site loads in https.

Each of those screenshots is quite different. Are you sure you don't just have some other configuration or content difference that would cause this?

Yes, they are different. The 1st is taken from the grav demo & the second is taken from my actual site. I have tested with & without the ssl certificate loaded. It shows exactly how the screenshots look like.