Thank you for your quick response. Whatever was causing the regeneration of the same “short-lived” access token was quite “stuck” – none of the obvious remedies would get rid of it.
As a last resort, I just deleted the Facebook application and recreated it, then the problem was solved. Luckily for me (and others!), you’ve organized things so that set-up is very straightforward, so recreating the FB application was no big deal.
Thank you again for your help.
