As reported on the German-language Wikipedia's feedback page and likely related to T214976: Can't select across block images in Firefox, it is not possible to select text across some references in VisualEditor. This has been reported for Firefox, I tested it on the most recent version on Windows 10.
Steps to reproduce:
- Open the Bamberg article
- Click 'Bearbeiten' to launch into the VisualEditor
- Place the mouse in front of Bamberg at the very beginning of the article text
- Attempt to select the entire introduction (press the left mouse button and drag the mouse to the end of the introduction, then release the mouse)
- Notice that only the part below the reference shown as [2] is highlighted
The expected outcome would be that the entire introduction is selected/highlighted.