[Koha] OPAC open in new window problem

Kia ora, Your assistance would be appreciated. I have set the system pref OPACURLOpenInNewWindow to 'do' which should cause URLs to open in a new window in the OPAC, but this is not happening. I have added ebooks but the link does not open in a new window. I am using 3.8.6 Debian packages. I found a bug report 5522 relating to this issue but it states ebooks were not affected, just Google preview. Does this warrant another bug report or is it covered in bug 5522. Many thanks, Clint Deckard. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.