If I have two windows open, one to Recently Active Questions, and in the other I ask a new question, the Recently Asked Question window has a message appear that there is one question with new activity, which if I click displays my new question at the top of the list. If I then click on "Questions" to refresh the page, my new question disappears for about a minute. Why does this happen?
This is essentially a technical issue, caused by our need to be preformant - that is, it helps us show you the page fast.
There are two aspects to the issue - one is caching. We save the current version of the list for a minute, and this is what everyone sees for that minute when they go to the page (or refresh it).
However, we also like to let people know if new stuff has come in - in real time. So we display a little banner that you can click on and that will fetch those questions and show them.
These are two separate mechanisms. If you click the banner, you see the new stuff, but if you refresh, you get whatever has been cached (which may not include newer stuff - that is younger than a minute).
Since the cache expires in a minute, those questions will show up on the newly cached version, as the newly cached page will have them.
Hope that explains things.