The basic issue is that gates essentially only look at the ticket type when determining whether it's valid at a given time or not, so they'll apply the same AM and PM peak restrictions to all Off-Peak Day tickets, regardless of origin and destination.My recent bugbear is the gateline at Manchester Victoria, which refuses to allow my ticket office-issued Cheap Day Return from Todmorden during the evening peak. It has a B1 restriction, ie not valid before 0930 but with no evening restriction. Whilst my tickets are bought against a Senior Railcard, this does not appear to be the issue - they work fine on other occasions when I return later in the evening, and of course it has happily accepted the outward portions on my arrival at Victoria.
There is a way round this with tickets issued on Smartcard, where it's possible to encode the actual restriction code, but I don't know if any Ticket Issuing Systems or Gates are configured to actually use that format.