By default, there is no used project directory filled in the Publisher properties.
The default value of the option in publisher.properties file:
# Determines path to MagicDraw used project directory. In case of several paths to use, they must be separated by a comma. Default: empty string
md2rhp.magicdraw.usedProjects.dir=
If used projects are not in the same folder than the current project, paths to needed projects must be set in publisher.properties file:
# Determines path to MagicDraw used project directory. In case of several paths to use, they must be separated by a comma. Default: empty string
md2rhp.magicdraw.usedProjects.dir=<Path to Magicdraw>\profiles,<Path to Magicdraw>\modelLibraries
If the md2rhp.magicdraw.usedProjects.dir property is not set in the publisher.properties file, the property is set to an empty string, by default.