I also cannot update one of the existing libraries I owned, even if I make changes to the master components in this XD file, the blue notification bar "Update your published library. Update Now" doesn't show up, but this library has already been published and is showing in the Libraries panel.
I tried to sign out and restart the Mac, but still not working. I'm on MacOS v10.15.4, XD v126.96.36.199, and Creative Cloud Sync 188.8.131.52.
Thank you for reaching out. It looks like you are using the older version of XD. Would you mind updating XD to the latest version using the steps mentioned here: https://helpx.adobe.com/creative-cloud/help/creative-cloud-updates.html?
Let us know if that helps.
Thanks for the reply, Harshika, auto-update has already been enabled.
XD has been updated to version 184.108.40.206 as of May 5, 2021, but the problem still exists.
I'm not sure why the blue bar would not be showing up, but see if this alternate process works: