<p dir="auto">This might be easier to demonstrate with a screencast, but try moving your mouse in and out of a tooltip parent really fast. From then on then on the tooltip can't tell if it's supposed to be open or not. If you try to open it again it closes after a split second before mousing out</p>
<p dir="auto">This problem have been around for quite some time, and issues have been created and closed without being fixed.</p>
<ul dir="auto">
<li><a href="https://github.com/twitter/bootstrap/issues/3712" data-hovercard-type="issue" data-hovercard-url="/twbs/bootstrap/issues/3712/hovercard">Disappearing Tooltips</a></li>
<li><a href="https://github.com/twitter/bootstrap/issues/4702" data-hovercard-type="issue" data-hovercard-url="/twbs/bootstrap/issues/4702/hovercard">Tooltips disappear when hovering hiding/showing them fast</a></li>
</ul>
<p dir="auto">Bug: Let's say you have an anchor-tag, which has a tooltip, enabled either from javascript or data-attributes. Place your mouse cursor over the anchor, and you'll see the popup. Now hover out and in again very quickly, and let the cursor stay on the anchor. Voilà, the <strong>tooltip disappears</strong>.</p>
<p dir="auto">Of course, you furiously start hovering out and in again (you <em>want</em> to read what the tooltip says), only to see the same thing happen over and over again, even if you are hovering much slower than the first time. The only way to see the tooltip is to remove your cursor from the anchor, wait a while, and hover again.</p>
<p dir="auto">I'll use a jsfiddle that has already been posted to demonstrate: <a href="http://jsfiddle.net/VXs44/" rel="nofollow">http://jsfiddle.net/VXs44/</a>. Otherwise, check your own <a href="http://twitter.github.com/bootstrap/javascript.html#tooltips">http://twitter.github.com/bootstrap/javascript.html#tooltips</a>, the same thing happens there.</p>
<p dir="auto">Tested in all 5 major browsers, latest versions, and it's only IE that doesn't have this bug, since it doesn't animate the tooltip. Setting animation to false also fixes the problem.</p>