The Shield version is broken too, for exactly the same reasons you stated above. Did the same, uninstalled, installed, deleted all offline content, still stuck on “Waiting to download”. I too also noticed this problem from 2164, and same problem on 2171. Synology version of 2171 is syncing fine. Also crossposted here: Sync stuck on "Waiting to Download" on 1.18.4.2171
