Selecting topics that are far down in the browse menu doesn't do anything. It seems to have something to do with them not being loaded, since it works if you have scrolled down to them first.

Steps to reproduce:

1. Go to https://www.mediawiki.org/wiki/Talk:Wikimedia_Engineering_Architecture_Principles
2. Click on "Browse topics"
3. Select topic "Coverage"

Actual result:
Nothing happens.

Expected result:
The page scrolls down to the selected topic.

Additional information:
It works if you select multiple times, e.g. selecting "Coverage", then another topic, then "Coverage" again.
Using Firefox 66.0.5.