Any idea what's causing this?
You probably had a random problem the first time you tried to update (an internet crash for example), and it saved files in the update folder, but corrupted, so it needs manual intervention to work now.
Watch this video (enable subtitles):
https://www.youtube.com/watch?v=gPwtCNIeFmg&list=PL2oNQ0AT7fx2ExiSNrfHUzga5GnogI4sh&index=18&ab_channel=Recalbox