I couldn't add this https://doi.org/10.5967/K8G44NGB via windows application but via online zotero login. So i suggest create an account and add it onlne.
@arjunnapmna: No, there's no reason something should work via the web library and not in the desktop app. I can add that DOI fine in the desktop app. If that's not working for you, provide a Debug ID for an attempt that fails.
thanks,
Arjun