After adding files as resources with qt_add_resources, these are visible in the project tree, but not available in the resource browser in integrated designer, e.g. when selecting the "..." for the "pixmap" property of a QLabel.

This happens with the qt_add_resources variant that directly takes a list of (e.g. image) files, not when adding .qrc files directly. E.g.

qt_add_resources(untitled "logo"
  FILES
    "images/qtlogo.png"
    "images/qtlogo@2x.png"
)