Saving a header file containing the "Q_OBJECT" macro to the project does not result in valid moc steps being generated for the file.
Adding an existing header file containing the "Q_OBJECT" macro to the project does not result in any moc_XXX.cpp files being added to the project, or any moc steps being generated for the file.
The linker then fails with missing implementations for QMetaObject etc.
I tried the old workaround of commenting out Q_OBJECT saving, uncommenting and then resaving.
This resulted in the "moc_MyObject.cpp" files being added to the vcxproj, but the actual moc "CustomBuild" steps were not added and so it could not be compiled.
I am not aware of any other methods of forcing the add-in to rescan the header file.