Has anyone seen the TOC in landscape or mobile mode add extra space between books (RH2015, Responsive HTML5 layout)?

Under certain circumstances, when navigating through the TOC in landscape or mobile mode (using Chrome and other browsers), extra space is added between certain books, depending on the order of the navigation, making the spacing inconsistent.

From what I can tell, when this occurs, the extra space is called by the following html (according to Chrome Inspect):

  <li class=“child max-height-transition show” …

However, where the space is hidden, as it should be, I get the following html:

  <li class=“child max-height-transition” …

In addition to the lack of “show”, the second html also activates the following CSS:

  div.toc-holder ul li.child:not(.show) {

    overflow-x: hidden;

  }

The latter behavior appears correct. However, for some reason RH is failing to hide the <li> class at certain times in landscape or mobile mode. Has anyone run into a similar issue? If so, have you come up with a resolution or at least figures out the cause?

Thanks.