I deactivated and reactivated my accounts today and noticed this when I was updating:
The "Updating your data" is the status of Sync to Mobile/Web.
I have always had Sync to Mobile/Web off.
Sure enough, I turn it on and see that 8 of my accounts (the ones I just activated for downloading) selected for Syncing to Mobile/Web.
This is a bug on two levels. First off, activating an account shouldn't result in it being selected for Sync to Mobile if Sync to Mobile is off. Second, if Sync to Mobile/Web is off it shouldn't matter if the accounts are selected for Sync to Mobile/Web, they shouldn't be synced.