In September 2022, all of my recordings disappeared from the planner... but I've managed to get them back.
I'm posting this here because it might be able to help someone else incase they get the same fault.
In Settings/System Settings - it showed the message "Connect a USB hard drive (HDD) to the box to be able to record programmes and pause live TV"
I turned the Freesat box off so it was in Standby.
I then pressed and held the Power button on the unit for 5-10 seconds until it forced the unit to shut down and reboot.
After the Freesat box had turned on, I didn't press any buttons for 10 minutes, just to give it time to fully power up.
(it may need a few seconds to load the recorded programmes on the planner, especially if you have a lot like me!)
I then pressed the Media button on the remote control to access my recordings and hey presto, they were all there again!