5Q68 Derby to WPS appears to be in the system as an "as required" service which has NOT been livened up, so does not appear to be running.Most units have had fairly extensive travels and it wouldn't have been at Long Marston if they thought it had a serious issue. The loco was scheduled to run around in that yard, it could be as simple as from the other end they couldn't get the brakes off. For the pathed speed it needs both the loco and unit brakes to be operational. Several moves have been cancelled after the loco got there so while uncommon it's not unusual.
Separately, a schedule change yesterday altered an existing GBRF path to go to Wimbledon Park Depot on Friday which might be another 701 delivery this time from Derby
Realtime Trains | 5Q68 1344 Derby Litchurch Lane to Wimbledon Park Depot Sdgs | 09/01/2026
Real-time train running information for 5Q68 1344 departure from Derby Litchurch Lane to Wimbledon Park Depot Sdgs on 09/01/2026. From Realtime Trains, an independent source of train running info for Great Britain.www.realtimetrains.co.uk
Perhaps they will try again next week ?