The version number of the latest release is 1.4.0 while the previous release was 1.30.0
This appears to cause confusion in the Ajour addon manager (and possibly others), making it think the addon is already updated while it is still on the previous release.

Releases on CurseForge go back all the way to 1.7.0 (November 2011).

I assume changing 1.4.0 to 1.40.0 should resolve the issue.

The newest version 1.4.1-bcc does show up as an update now, so I suppose this issue is resolved.