I am also having this issue with the Jarvis theme. There is a mobile-only navigation that is hidden by theme and appears as
<select class=”selectnav” id=”selectnav1″>
in the code. Using the Inspect Element tool I can see that as soon as the lightbox opens
style=”display: inline-block;”
is appended to this nav. Even after the lightbox is closed this style remains attached to the nav and it is visible.
Example: https://test.bluelightscene.com/photos/