Software is not preparing any updates?

Hi, I've noticed that it's been a while since the last time I've installed updates. I can see that gnome-software-40.0-2.fc34 is checking for updates and displaying updates to be downloaded in its Updates tab:

But it doesn't seem to be preparing the updates in order to ensure users are prompted to install updates when powering off. Poking around in dconf-editor, I see my install-timestamp is set to 1617660345, which is Mon Apr 05 22:05:45 2021 UTC. Uh-oh: that's even longer than I had thought! When there are no urgent updates available, we are supposed to prepare updates once every two weeks. I would definitely have installed updates had they been prepared, so I'm almost certain that no update is being prepared.

My check-timestamp is 1620996916, which is Fri May 14 12:55:16 2021 UTC. So that's fine. My online-updates timestamp is 1620737760, Tue May 11 12:56:00 2021 UTC, also fine.

If I manually click on the Download button in the updates tab in GNOME Software, then it is able to successfully prepare an update, and I can install the update from the GNOME Shell power off dialog as usual. So I think the problem is GNOME Software is getting confused and never preparing the update for some reason. This must be a regression in 40, because in 3.38 updates were prepared way too frequently.

CC @aday