Content folder picker for new channel is not initialized correctly when dialog for blueprint without a picker is selected first

The 'content folder picker' in the 'add channel' dialog is not initialized correct when first a blueprint without a picker is selected. In that case, the initial value in the picker is not shown and the picker widget is very narrow (see screenshot).

However, the correct value is used internally and the channel can be created without problems. It's just the UI that is not correct. Also when another folder is picked, the widget is updated and the picked folder path is shown correctly.

Steps to reproduce:
1. log in to the GoGreen CMS as admin or editor
2. click the 'Channel Manager' perspective
3. click 'Add channel'
4. click 'Next'
5. click 'Previous'
6. select the 'Website' blueprint
7. click 'Next'

Expected behavior: the dialog now renders, besides the name and the url field, also a picker with the default value '/content/documents/hippogogreen'
Actual behavior: the dialog renders a very narrow picker widget and the default value is not shown.