Sticky elements not functioning correctly when there’s more than one

I am working on a site that has a sticky nav and sticky social sharing buttons, and they seem to interfere with eachother on mobile. On the homepage the sticky nav works as expected, but on the post layout where the sharing is active, there are 2 issues:

1. Nav no longer sticky when scrolling down, only up
2. The sticky sharing buttons jump around depending on whether I scroll up or down

To view the password protected staging site please use “thenewqx” for both fields. Thanks in advance for helping me resolve this. Layout is WIP. ??

The page I need help with: [log in to see the link]