i recently started to receive error notices about my my synching that started in Oct

I suggest you reset your cloud data: select Edit > Preferences..., Mobile & Web, and Reset your cloud data

If the issue persists, I suggest deleting the Quicken Cloud dataset (aka cloud account) associated with the Quicken file.  Note: You need to open another Quicken file to delete the appropriate cloud account.  You may want to review: https://www.quicken.com/support/how-edit-or-delete-your-cloud-datasets-quicken-windows

The other Quicken file needs to have a distinct file identifier so that we may delete the cloud account associated with the original Quicken file.  For example, you may create a new Quicken file (select File > New Quicken File...) without any accounts, enable sync in preferences so you may view and delete the cloud account associated with the original Quicken file. 

After deleting the cloud account, you do need to open the original Quicken file and sync for the accounts to be available on the web or through the mobile app.  The initial sync may take some time to complete.

If the issue continues to persist, I suggest you contact Quicken Support: https://www.quicken.com/support/quicken-support-options