In qtquickcontrols2, the fallback takes priority over the style itself if the fallback is registered last. To reproduce, checkout https://codereview.qt-project.org/c/qt/qtquickcontrols2/+/297488/91 and run the styleimports test with this argument:

select:"control=Action,style=data,fallback=empty"

The workaround is to register the fallback import first:

https://codereview.qt-project.org/c/qt/qtquickcontrols2/+/297488/91..92