Settings > Users> Permission Sets: No scroll bar appears when list is long

I have seen this happen in both chrome and firefox, and across all different apps. The attached Jing is an example.

Search for settings
select permisions
Expected result: the whole list appears, or a scroll bar allows scrolling through the list.

Actual result: the list ends at the bottom of the window. Additional items only revealted by making the text smaller (and smaller).
https://www.screencast.com/t/VsTPIOhq