In ...\Modules\AppUtil\src\mitkBaseApplication.cpp ln 531 the QStringList of pre load libraries is joined with "," to a QString.

d->m_FWProps[ctkPluginConstants::FRAMEWORK_PRELOAD_LIBRARIES] = preloadLibs.join(QString(','));

But in ctkPluginFrameWorkContext ln 119 a QStringList is expected with pre load libraries as items but a due to the join a QString is received.

This leads in the end to an error message "Pre-loading library <preloadlib1>,<preloadlib2> failed: <...> Check your library search paths.". because the previously inserted QString <preloadlib1>,<preloadlib2> ends up as one item in the QStringList.

-> So multiple libraries currently can't be loaded.

Solution is to remove the join command and to insert the QStringList in mitkBaseApplication:
d->m_FWProps[ctkPluginConstants::FRAMEWORK_PRELOAD_LIBRARIES] = preloadLibs;

This way the QStringList is inserted to the QVariant and later on also reveived withing ctkPlugionFrameworkContext.

I will create a pull request on my mitk github fork for it once I have the bug number.
;) Ingmar