Some saved games not visible in in-game list

I’m having problems loading some of my saved games in AoE:DE because they don’t appear in the in-game list of saves. I know the save files exist, because when I open the saved games folder I can see them there. This doesn’t affect all of my saved games - only a few of them.

Looking at the files, they don’t seem to be corrupted in anyway. The only thing I’ve noticed is that the date modified on the saved games I can open is the time I last booted up the game, whereas on the saved games I can’t open it’s the date/time the saves were made.

Can anyone suggest a way to fix this?