Cannot select a folder for uploading an image in the Image Picker

STEPS:
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a)

• using myarticle2, activate field Body and click the Insert/Modify Image button
• use Browse to access an image file of a supported format
• back to the ImagePicker dialog click Upload
  => as a result the image is loaded and its file is visible next to the default 'hippos' folder

b)

• from within the Image gallery click to add a root folder, we call it giraffes
• using myarticle2, activate field Body and click the Insert/Modify Image button
• double-click Giraffes to open it with the intention to upload an image to that folder
• use Browse to access an image file of a supported format
• back to the ImagePicker dialog click Upload (making sure the path to the image file is shown in the corresponding field)
  => nothing happens