With VS 16.3.2 and QTVSADDIN 2.4.1 or 2.4.0 an error occurs when importing pro files that include MS specific lib files. For example:
LIBS += -ldinput8
Will result in a error importing the pro file: "Invalid character in path". My workaround was to move it to a header file with #pragma comment (include, "dinput8.lib"). This occurs with both MSVC 2019 and 2017 after updating VS 2019 to 16.3.2.