Not sure if this really is a bug, but ...
When I select a 24 px Size and combine it with [x] "Render from TrueType outline", Then I get 50 times out of 20000 chars an entry of height=25 and 6 times out of 20000 chars an entry of height=26 in the corresponding .fnt file.
However, when I deactivate the [ ] "Render from True Type outline" option, all generated entries in the .fnt have <= 24 height.
Is this the expected behavior or a bug?