I tried setting the update URL to use http instead of https, but to no avail.
Also I've run through the latest logs after hitting the "Check Now" button a few times and, other than the issue here, everything looks as expected (I can't post the log here without redacting information which I don't have the time to do unfortunately).
danielbeck Any other possible workarounds? I'll update manually for now but this naturally doesn't scale well and I don't know which other plugin updates may be missing.
I see updates for other plugins that are fairly recent (this week) so I'm left to assume update center is functioning correctly, but that the build name setter plugin update details, and potentially others, are not being returned.