Using MAC OS X 10.10.5; XOJO 2015 r3.1
Just tried a program with a native XOJO report and the font size of all the report items seems to be scaled down to about ? of what I specified (64 bit).
To test my sanity, I then tried the ListBox report example provided with XOJO - and changed the Last Name, First Name title(s) font size to 24. Ran the program and this showed the same scaling of the font size (32bit).