Some additional info from my ubiqity.log - I hope this helps someone smarter than me to troubleshoot:
[ERROR] 12f08740b5a [13/09/22 10:43:05.174] 364.main copy_mme_bag:229 copyPreferredMobileMeName failed
[ERROR] 12f0ac48f39 [13/09/22 10:43:05.213] 364.main ubd_main:2705 null personid
[ERROR] 12f0dbeb2bc [13/09/22 10:43:05.263] 364.main db_prepare_blocking:1278 conn#0 active (create|first-open|in-txn|for-update|can-rollback), owner:main, retains:1, changes:0-0 can't prepare 'select max(local_rank) from item_table;': db error 1 (no such table: item_table)
[ERROR] 12f0dbfa6ee [13/09/22 10:43:05.263] 364.main iidb_has_schema:4773 failed to prepare 'select max(local_rank) from item_table;'
[ERROR] 12f0eb9976b [13/09/22 10:43:05.280] {FFFFFFFF} 364.main copy_all_appleid_identities:830 _CSCopySecIdentityForAppleID failed for account XXX@XXX.com (canonical account XXX@XXX.com): error The operation couldn’t be completed. (OSStatus error -1.)
[ERROR] 12f0ee96cde [13/09/22 10:43:05.283] {FFFFFFFF} 364.main copy_mme_bag:229 copyPreferredMobileMeName failed
[ERROR] 12f0f75b37c [13/09/22 10:43:05.292] {FFFFFFFF} 364.main ubd_main:2876 No identities defined.
[warn] 12f0fbaf625 [13/09/22 10:43:05.297] {FFFFFFFF} 364.main set_computer_name:114 Not setting the computer name without a collection/config only mode
[ERROR] 12f111c00e0 [13/09/22 10:43:05.320] {FFFFFFFF} 364.com.apple.ubiquity.SRConnection.callouts.0x7f87f4907970 get_collection_status:939 no collection config found for default
[ERROR] 12f1138d00a [13/09/22 10:43:05.322] {FFFFFFFF} 364.com.apple.ubiquity.SRConnection.callouts.0x7f87f4907970 get_collection_status:939 no collection config found for default
[ERROR] 1416c009170 [13/09/22 10:44:24.154] 364.main ubd_main:2695 personid: 57681912
[ERROR] 1416c05b344 [13/09/22 10:44:24.154] 364.main compare_prefs_uuid_to_hw_uuid:701 hwUUID not present
[warn] 1416ebe0302 [13/09/22 10:44:24.200] 364.main find_existing_identity_unsafe:1096 Can't find identity. (error -25300 from SecItemCopyMatching)
[ERROR] 14182950a8a [13/09/22 10:44:24.533] 364.main db_prepare_blocking:1278 conn#0 active (create|first-open|in-txn|for-update|can-rollback), owner:main, retains:1, changes:0-0 can't prepare 'select max(local_rank) from item_table;': db error 1 (no such table: item_table)
[ERROR] 1418295e32f [13/09/22 10:44:24.533] 364.main iidb_has_schema:4773 failed to prepare 'select max(local_rank) from item_table;'
[warn] 1419d84ec12 [13/09/22 10:44:24.985] {0EA89BDE} 364.connect-(null)-5c43def8 find_existing_identity_unsafe:1096 Can't find identity. (error -25300 from SecItemCopyMatching)
[ERROR] 141a01b8206 [13/09/22 10:44:25.028] {0EA89BDE} 364.com.apple.ubiquity.SRConnection.callouts.0x7faeabc36bc0 get_item_list_for_path:748 no item exists for relative path /com~apple~TextEdit
[warn] 142206fdd3a [13/09/22 10:44:27.181] {0EA89BDE} 364.mme-reconnect-queue deferred_connect_to_mme_queued:750 can't find the mme peer to reschedule a sync, forcing a reconnection
[ERROR] 1423d8b101b [13/09/22 10:44:27.670] {0EA89BDE} 364.connect-(null)-5c43def8 _perform_one_synchronous_request:675 error for https://p02-ubiquity.icloud.com:443/ub/57681912/rwsync/0EA89BDE-46B6-EB3F-7859-F F908758B5D5: status 503
[ERROR] 1423d8d214b [13/09/22 10:44:27.670] {0EA89BDE} 364.connect-(null)-5c43def8 _handle_mme_http_error:443 Got MMe Service Unavailable, retrying connection after delay
[ERROR] 1423d8fd313 [13/09/22 10:44:27.670] {0EA89BDE} 364.connect-(null)-5c43def8 send_init_command:1001 perform_synchronous_anon_request to https://p02-ubiquity.icloud.com:443/ub/57681912/rwsync/0EA89BDE-46B6-EB3F-7859-F F908758B5D5 failed
[ERROR] 1423d90383d [13/09/22 10:44:27.670] {0EA89BDE} 364.connect-(null)-5c43def8 connect_to_endpoint:468 send_init_command failed
[ERROR] 1423db3d243 [13/09/22 10:44:27.672] {0EA89BDE} 364.connect-(null)-4e38dd60 _perform_one_synchronous_request:675 error for https://p02-ubiquity.icloud.com:443/ub/57681912/rwsync/0EA89BDE-46B6-EB3F-7859-F F908758B5D5: status 503
[ERROR] 1423db490ac [13/09/22 10:44:27.672] {0EA89BDE} 364.connect-(null)-4e38dd60 _handle_mme_http_error:443 Got MMe Service Unavailable, retrying connection after delay
[ERROR] 1423db5ef14 [13/09/22 10:44:27.672] {0EA89BDE} 364.connect-(null)-4e38dd60 send_init_command:1001 perform_synchronous_anon_request to https://p02-ubiquity.icloud.com:443/ub/57681912/rwsync/0EA89BDE-46B6-EB3F-7859-F F908758B5D5 failed
[ERROR] 1423db64d36 [13/09/22 10:44:27.672] {0EA89BDE} 364.connect-(null)-4e38dd60 connect_to_endpoint:468 send_init_command failed
[warn] 1f44eae2317 [13/09/22 11:04:35.542] {0EA89BDE} 364.mme-reconnect-queue deferred_connect_to_mme_queued:750 can't find the mme peer to reschedule a sync, forcing a reconnection
[ERROR] 1f46a9e36cf [13/09/22 11:04:36.010] {0EA89BDE} 364.connect-(null)-2ae47cca _perform_one_synchronous_request:675 error for https://p02-ubiquity.icloud.com:443/ub/57681912/rwsync/0EA89BDE-46B6-EB3F-7859-F F908758B5D5: status 503
[ERROR] 1f46a9f762a [13/09/22 11:04:36.011] {0EA89BDE} 364.connect-(null)-2ae47cca _handle_mme_http_error:443 Got MMe Service Unavailable, retrying connection after delay
[ERROR] 1f46aa1fb02 [13/09/22 11:04:36.011] {0EA89BDE} 364.connect-(null)-2ae47cca send_init_command:1001 perform_synchronous_anon_request to https://p02-ubiquity.icloud.com:443/ub/57681912/rwsync/0EA89BDE-46B6-EB3F-7859-F F908758B5D5 failed
[ERROR] 1f46aa29b93 [13/09/22 11:04:36.011] {0EA89BDE} 364.connect-(null)-2ae47cca connect_to_endpoint:468 send_init_command failed