Code Coverage doesn't always work on EAP

First off, I'm posting this here instead of the issue tracker, because there's a chance that I'm doing something wrong.

I'm relatively new to unit testing, and I'm trying to use dotCover to continuously unit-test my project. I am using the "Unit Test Coverage" tool window to keep track of what's already covered, and what isn't. The way I would "update" the data shown on this window after writing a batch of new tests, is by right clicking the test project (i.e. root node) on the unit tests tool window, and then clicking "Cover Unit Tests", or alternatively pressing "Ctrl+U, K", which triggers a full code coverage for all existing tests in the solution.

The expected result of this action would be the Coverage tool window refreshing with the new percentages, immediately after the last test completes. However this doesn't always happen, meaning that sometimes I have to re-cover the entire project, and wait for all the tests to complete again, which can take up minutes. What usually happens instead after the first time I run a coverage, is all percentage bars are reset to 0% on the coverage window, except for the testing project itself, which isn't very useful. Running the same coverage again usually fixes the problem (but not always).

Is this intended behavior, or am I doing something wrong?