iCloud drive not updating on Mac

I thought it was great when Mac OS Sierra moved my entire Documents folder to iCloud Drive. I assumed it would essentially work just like Dropbox, and that my documents would be kept synced between my iMac and my MacBook. But it doesn't seem to work consistently, and I'm worried I'm going to suffer data loss as a result.

I use Quicken 2017, normally on my iMac, and my Quicken data file is stored on my iCloud drive (in a subfolder of my Documents folder.) But when I travel, which is frequently, I need to be able to use that data on my MacBook. That worked great when I stored the file on Dropbox. But now that I've moved it to iCloud drive, the file I see on my MacBook is a much older version than the current version that I saved on my iMac, without recent changes I have made. Worse yet, if I accidentally open that file, Quicken will update it and create a "newer" saved version based on that obsolete file, and when this happened to me, I was in a panic that I was going to get home and discover that my file on the iMac had been overwritten by this older file (now with a newer date on it.)

Fortunately, that didn't happen, because iCloud Drive didn't update going that direction either.

My MacBook is not awake much of the time, and so I understand that it might take some time to synchronize the iCloud Drive files (though I see no indication this is happening.) But even after being on and awake for 24 hours or more, the files don't update. Yet something is happening — if I create a file on one machine, it will appear on the other, but often won't get updated if I change it.

Some files show up in the finder with a cloud icon next to them. There's no explanation of what this means, but I assume you click that to download the latest version? (What, it's not automatic?) But that doesn't work either.

Basically I'm concluding that iCloud Drive is kind of worthless and I guess I'll move back to using Dropbox, which is annoying because I'm spending money every month for the iCloud storage. Am I missing something here? I have plenty of iCloud drive space, and both computers are running the latest Sierra release.