[Koha] 856 - Electronic access problem

Hi list, This week we have upgraded our koha installation from 2.2.6RC2 to 2.2.8, and since then we are seeing the following issue: The field "856 -Electronic access" (containing a url) no longer displays as a clickable hyperlink, but as clear text, like this: http://intech009.intech.unu.edu/koha/electronic-access.png This used to work in 2.2.6RC2. Any ideas what happened? Kind regards, Mourik Jan Heupink