We’ve had terrible trouble, Durham office. Birth certificate was a replacement issued by Scotland’s National Records Office and has been used previously for 2 passport applications with no problems. This time someone decided it was a photocopy and asked for original (misplaced some time ago) and some additional info. Information has been posted (arrived 24 May according to tracking) and also emailed (30 May) and have heard nothing since. I hope you get it looked at in time since you are travelling.