Why will the forum ticketing site not sell me an LNWR only super off peak for the 1558 from Tile Hill changing at Rugby?

The restriction code LG:

The restriction code LG:
The last line seems to suggest this itinerary should be valid.Not valid for travel on services timed to arrive London Terminals before 13:00.
Not valid for travel on northbound services timed to depart any station before 10:30.
Not valid for travel on services timed to depart the origin station on the ticket after 15:59 and before 19:01 in either direction.
A connecting service can be used to complete a journey begun at a valid time.