Barrie,
What effects do you have when you...
-- delete the (errant) link to the Ibidem record
-- refresh the Ibidem Table View
-- and the create an entirely new link?
If the new link works, copy and paste from the original NB document. If this works, delete the previous NB doc. This is not so much a solution as a way to get over the obnoxious cases.
Mark