When building Pyside with the following command line:

python setup.py build --relwithdebinfo --module-subset=Core --qmake=%QTPATH%\bin\qmake.exe --openssl=%OPENSSLPATH%\RelWithDebInfo\bin --build-tests --ignore-git --parallel=%NUMBER_OF_PROCESSORS%

PySide2 is built and installed to pyside3_install, however the PySide2 support module which provides the PySide2 _feature_ support is not installed there.

It appears that this is only installed in the creation of the wheel, which I do not perform due to the specifics of how we install PySide2 in a Python installation that is embedded in an application (Autodesk Maya).

Manually copying the PySide2/support module into the site-packages/PySide2 dir during the packaging process corrected the issue, but I think the fix really needs to occur inside the PySide2 build process.

When starting the application with embedded Python interpreter, and PySide2 is imported, the following message is shown:

Qt 5.15.1 (Python 2): _feature_ could not be imported when starting maya/mayabatch.

Steps:

1. Start Maya or mayabatch with Qt 5.15.1

Result: A following error is returned:

__feature__ could not be imported. This is an unsolved PyInstaller problem.