Hey there,
I checked and I am able to sync with the cloud. Is it hanging, or just blank? Have you gone into settings and verified that your calendar is showing? Lastly, have you tried a manual sync from settings?
Mind you I am working from a nandroid of a fresh install. So if you installed the HTC calendar, its probable that the new calendar and provider are conflicting with old data. A wipe may be in order. Make a nandroid just in case that doesn't fix it.
Keep me updated.