I was looking to book a ticket on Caledonian Sleeper's website, and manually choose one of the single seats as I would be travelling alone. Once you've chosen your journey date and filled in your details, it allows you to change the automatically allocated seat.
However for every journey I have tried (including some next week) it seems like every seat is available apart from 2A and 2B. I'm suspicious that there is such high availability, particularly when it says "only one seat left" or similar. It seems to accept changing your allocated seat to any other, and as far as I can tell you can proceed to payment with that selection.
Has anyone encountered this issue before?