When you have a header file with a different base name from the CPP file, the Visual Studio Add-In doesn't fully update the project's Generated Files (adding the appropriate moc_...cpp files) and doesn't correctly create the Custom Build Rule.

First, create a new Qt Application, using the default selections. Create a header file, say "addinbugtest_p.h" and declare a class with a Q_OBJECT macro in it. Ensure the file "addinbugtest_p.cpp" doesn't exist in the project. When you save, the Add-In update process seems to create a moc_addinbugtest.cpp entry within "Generated Files/Debug", but the Release moc file is missing. If you look at the custom build rule that is generated on addinbugtest_p.h, you will find no commandline.