According to the third picture on the Firefox devtools documentation page, the break down of "samples" should show a "samples" value for each row.
When I run Firefox devtools all break down rows shows "0" for the "samples" value - is this an error? Should the break down not show any values for "Samples"? Am I doing something wrong here?
This seems to have been a limitation of the invert algorithm since the panel's beginnings. Disabling Invert Call Tree in the profiler options shows the samples and self time/cost correctly.
There is a new profiler in the works that has a much more advanced Call Tree. It can be installed from here: http://profiler.firefox.com/
Thanks to Harald Kirschner and Julien Wajsberg for the help!