If there is no space the index is hidden by default.
In this case, a dynamic bar shows up at the bottom with an index button. Like here.
The above only happens if there is 1 replies or more. Most of my docs have zero replies, like here - in this case the same index button does not show up.
Not sure if this is a bug, or should be a feature 
@awesomerobot I think we we recently refactored this, is this an on-purpose omission?
I totally get that documentation categories may want this (and to restrict replying)
Unless I misunderstand this can already be prevented with permissions or closing topics 
Hmm I see, this is narrow views in desktop view, not mobile view, right?
It seems by default we hide the topic progress bar on desktop with < 2 replies, so because of this the table of contents can’t appear.
Curiously, we don’t do this on mobile… so maybe we should remove it.
const hideOnShortStream = !this.site.mobileView && filteredPostsCount < 2;