Sync Error: budget category groups download: unexpected GET tags response

I'm posting this as another solution for anyone else who runs into this problem. I've seen this same issue posted on these forums but none of the suggestions helped. After going back and forth with Quicken support for over an hour, I was told they still had no idea what would cause this. We looked through all my categories and tags (although I don't know how we would have been able to diagnose a bad tag or category just by looking at it in the app). We disconnected and reconnected the cloud services. Restarted the app. Nothing helped.

Finally they gave this solution: Go to a backed up version of the file from before the problem started appearing. This was a very unattractive option as I'd just spent hours and hours over the past week catching up on my data and I didn't want to spent several more days repeating that work.

The solution that worked for me:

(Note: this is for Quicken Classic Premier for Mac desktop, version 7.8.0, and it successfully restored all my accounts and transactions, including categories, tags, memos, and action field data — however, it didn't work for investment accounts, which you'll see below)

1. Export Quicken Transfer File (QXF) from the File menu
2. Create new Quicken file and select "Start from scratch"
3. Import "Quicken Windows file (QDF, QXF)" and select the file you just exported
4. After it finishes the import, dismiss the popup that suggests reconnecting your accounts
5. Instead, reconnect all your synced accounts one by one
6. If you had any investment accounts, then like me you may find the market values and holdings are completely wrong. In this case, delete the accounts and re-add them. (This was acceptable to me because I'm not as interested in historical investment data as I am in budgeted accounts.)
7. Delete or archive the old Quicken file and its related cloud account

And just a note to any Quicken staff: we could never reproduce the error, which tells me you have a troubling bug still lurking somewhere. Hopefully I never see it again, but if I do, I'll be trying my solution above again.