No Valid Settings found when importing a pro or qmlproject to QDS or Qt Creator

When importing a .pro file to QDS (a project created with Qt Creator), I get a warning that there is no valid settings file (a .user file exists, created by Qt Creator).

When importing a .qmlproject created with QDS to Qt Creator, I get a warning that there is no valid settings file. (a .user file exists, created by QDS).

Maybe I'm not using the two programs correctly as I would expect. But as recommended I'm having the same project opened as developer in Qt Creator, and as a designer I have the same project opened in QDS. 

Maybe the two program shouldn't share the same .user extension (and format?) if they are not compatible with each other? 

The .user file created by QDS starts with: 

<!DOCTYPE QtCreatorProject>