This'll be fixed in a PR I'm just about to send in, just documenting it here for reference.

The XML definition of the blip frame sets the alpha of the widget to zero by default. This is normally fine, since the animations would then set it to 100% alpha when they finish executing.

The issue is when you've got UI animations disabled - the alpha never gets changed from zero, so tooltips work just fine but the blips won't be visible.