I’ve had trouble with one of my macs not syncing to iCloud.
Specifically, if I update a document on my second mac, it goes to iCloud just fine (I can see the updates on iCloud.com, my iPhone, and my iPad) but I don’t get the update on my first mac.
The best workaround I’ve found is to make sure both macs are awake and online when a document is modified. it seems if a mac is offline and misses the new data push from iCloud, the mac never requests new data from iCloud.
if one mac is offline when I change a document and I need the changes on that sleeping mac later, the best thing to do is modify the document again (via the other mac or iCloud.com) after the sleeper wakes.