To reproduce:

1. Go to https://en.wikipedia.org/wiki/Nuer_language (or any other article with 14 links)
2. Click CLL's "6 more" button
3. Click on Tagalog.
4. Return back to English.
5. Click on Brezhoneg.
6. Return back to English.
7. Click on Polski.
8. Return back to English.
9. Go to the language search box and type "th".

Observed: A language that starts with "th" is not found (as expected). More than 4 languages appear in the "You may be interested in" list, but only the first three are actually seen. I cannot see more links. There is no scrollbar and I cannot use the two-finger scroll gesture on the touchpad to scroll there.

I tested this using Firefox and Chrome on a Mac.

Screenshot: