I'm on 10.57.5 and I've been getting the same issue in the past 3 days. Sometimes it syncs with no issues but sometimes it just pauses until the whole evening and I lose the sync between my devices when this happens. I've been a Personal account user for the past 3 years and I'm really considering migrating to another app if a paid subscription does not provide me with the stability and confidence to host my notes on the Cloud.