You're right -- when the action sends output to a file and the file written is larger than 50K, most of the file contents would be logged even if logging of step output was disabled.
The main download at
http://www.kinook.com/Download/VisBuildProEval.exe has been updated with a fix for this issue (VisBuildBld.dll v6.3.0.2 in Help | About | Install Info after installing).