The changes file for the Add-in version 1.1.1 states:

"As there is no way to avoid the expansion of generated files filter when the project is built the first time, the generated files are collapsed after the build has finished (QTBUG-4750)."

The problem is that all of the other folders will be expanded instead now. When creating a new project using the Add-in, making sure all subfolders are closed and then buiding the solution, all of the folders, except the generated files subfolder, will be expanded. This also happens when doing a clean of the project and when doing a build again.