Hyperlink tooltips are flaky, don't always appear

One more random data point in case someone finds it useful: I seem to be in an in-between world where sometimes it works and sometimes it doesn't. It seems that if I move the mouse in from the left side of the screen on the same line as the link, I usually get no tooltip. If the mouse comes from the bottom (or otherwise goes over non-link text) before hitting the link, I do get the tooltip. Even coming from the left, I still get it maybe 10% of the time (estimated).

from @zb140