If the note referenced by 32863486eb8246a6b56d3b1eddfd15e9 is not that big and if each time you sync you get a 507 error for a different note I can only suggest that you consider the 507 error itself. By that I mean check that your webdav server actually has (or can access) the available storage space you think it has. Additionally, the server may have lots of space but the webdav account itself may have a much smaller quota.