I believe the recording schedule that you see is only part of the the picture. There are potentially many series recordings that have been set and are not showing as no new episode of the series exists in the schedule of upcoming programmes. Those historic series recording only lapse after x weeks/months (x defined by Youview).
Historically it's been the case that if a box stops recording then it's been down to the index structure on the disk being corrupt which only a full reset , wiping all existing recordings , will fix.
I'm in the same boat as don't want to lose some existing recordings. Like you I also lost all scheduled recordings from the planner. It appears from all the comments a full reset is the only way to recover the record function. Thanks