Hi all - just adding my name here to this issue list as well.
I have been having the same issue - on box firmware 4.31, completely unable to stream any recordings from the main box showing the 'not at home' error.
Same issue in diagnostics with CPE IP showing as 'Unknown'. Yet appears fairly easy to find the CPE IP - it looks to have registered on the router with a dns name of virgin-tv-1, so the network is easily able to access it simply by querying this DNS name. It will allow me to push/pull programmes from the app to/from the main box.
Hoping someone from Virgin can step in and provide an update here - it's very frustrating having issues such as this, especially when telephone support are completely unable to assist.
I can also confirm that the latest update on iOS (4.32.1) has resolved this issue for me on the latest iOS (14.6)
The only thing that may be of use for anyone having the same issue - on one of my devices I did have to delete the app fully and reinstall from scratch to get it working but now both iPhone and iPad are working.