If you select data nodes in the Data Manager by the mouse, the Data Manager sets their "selected" property accordingly. However, if you set the Data Manager selection through BlueBerry, the properties are not updated.
Here is a fix for this:
https://github.com/NifTK/MITK/commit/39432a7bde691e3b733c6a577d95e202bf8ca9a1
This depends on T22962 for which I also provided a fix. That fix has to be applied first.
This is also related to T19500 that ensures that the data manager tree view highlighting is updated after setting the "selected" property directly. (I do not remember if it triggers updating the BlueBerry selection of the Data Manager, maybe that's missing.)