Missing plugins.qmltype from Qt Quick components (ios, iosemulator)

Running the new 5.7.0 Beta / Qt Creator 4.0 RC 1 distribution on OS X 10.11.4. When trying to create a sample Qt Quick Labs project targeting ios, Qt Creator fails to enter Design mode with error "QML module does not contain information about components contained in plugins"

When looking for plugins.qmltypes files, they appear to be missing from 5.7/ios, but are present in the 5.7/android_armv7 subtree.

Copying missing files from Android resolves the Qt Creator error, but the Designer fails to add imported controls to the controls pane.