I have wondered this for a while now - sometimes when using the developer console, and running tests, the console stops listing the percentage of coverage next to "All Tests" in the upper left corner. I can't find any rhyme or reason to this, but it can be very annoying when trying to determine the effect of changes made to test classes. You run tests once and it says 70% - great - then you simply run it again, and it says nothing at all. Why?
Anyone ever figured this out?