qmlplugindump cannot find dependency HelperWidgets

I upgraded from Qt 5.4 to 5.5.

When I call qmlplugindump I get the following error:

[-][.../Qt/5.5/gcc_64/bin]:: ./qmlplugindump -v MyPlugin 1.0 ~/MyPluginSource > ~/Bla
parsing <outputOfQmlimportscanner> skipping MyPlugin
appending dependency QtQuick 2.0
appending dependency QtQuick 2.4
appending dependency QtQuick.Layouts 1.1
appending dependency QtQuick.Controls 1.3
appending dependency QtQuick.Window 2.2
appending dependency QtQuick.Controls.Styles 1.1
appending dependency QtQuick.Controls.Styles 1.2
appending dependency QtQuick.Controls.Styles 1.3
appending dependency QtQuick 2.2
appending dependency QtQuick.Controls 1.2
skipping private dependecy QtQuick.Controls.Private 1.0
appending dependency QtQuick.Window 2.1
appending dependency QtQuick.Controls 1.4
appending dependency QtQuick.Controls.Styles 1.4
skipping private dependecy QtQuick.Extras.Private 1.0
appending dependency QtGraphicalEffects 1.0
appending dependency QtQuick.Extras 1.4
appending dependency QtQuick.Extras.Private.CppUtils 1.0
appending dependency QtQuick.Extras.Private.CppUtils 1.1
appending dependency QtQuick 2.5
appending dependency QtQuick 2.1
appending dependency QtQuick.Controls 1.1
appending dependency QtQuick.Layouts 1.0
appending dependency QtQml.Models 2.2
appending dependency HelperWidgets 2.0
QQmlComponent: Component is not ready
file://../Qt/5.5/gcc_64/qml/loaddependencies.qml:2:1: module "HelperWidgets" is not installed

With grep I found that HelperWidgets qmldir is located at
.../Qt/Tools/QtCreator/share/qtcreator/qmldesigner/propertyEditorQmlSources

So... I basically added that directory to the environment variable QML2_IMPORT_PATH and I can run qmlplugindump almost successfully:

QQmlComponent: Component is not ready
file:///...Qt/5.5/gcc_64/qml/QtQuick/Controls/Menu.qml:149: TypeError: Cannot read property '__contentItem' of null

Right now, I'm basically unable to continue to work on my project. That's a bit... problematic. I'll have to downgrade to 5.4 for now and hope that the issue gets fixed with the next release.

Thanks in advance. I'll try my best to provide all the information needed.