ContentController assetUploaded SignalSlot not working for Assets


I followed this HowTo ( to tag my assets automatically.
This SignalSlot (ContentController assetUploaded) is emitted for the properties of these types:
type: 'Neos\Media\Domain\Model\ImageInterface’
type: 'Neos\Media\Domain\Model\Asset’
type: array<Neos\Media\Domain\Model\Asset>

Now I want to decide which tag to use depending on th propertyName. But this is only submitted when the property is of type: ‘Neos\Media\Domain\Model\ImageInterface’.
Is there a reason why ‘Neos\Media\Domain\Model\Asset’ do not submit the propertyName, or is this a bug?