Good day, muon-discover has not been reporting updates to me for quite a while, stating that the system was up to date, when requested to update. Only running 'apt-get update' directly revealed, that actually there is a hash-sum mismatch and old package lists are used instead of recent ones. I guess the correct behaviour for muon-discover would also be to inform the user of the problem instead of pretending that everything is okay and there are just no updates available. Thank you for looking into this.
Using PackageKit nowadays, shouldn't have this problem anymore.