I seem to be seeing:
2024-07-08 16:55:03.394934+0100 0x11fe8b Activity 0x800000000006f750 468 bird: (CloudDocsDaemon) dl-content
2024-07-08 16:55:03.395379+0100 0x11fd38 Activity 0x800000000006f751 468 bird: (CloudKit) client/fetch-records
2024-07-08 16:55:03.823301+0100 0x11fd38 Default 0x800000000006f751 468 bird: (CloudDocsDaemon) [com.apple.clouddocs.default] [WARNING] failed downloading 1 documents (<private>) in <private>: <private>
2024-07-08 16:55:03.837281+0100 0x11fd6f Default 0x0 468 bird: (CloudDocsDaemon) [com.apple.clouddocs.default] [NOTICE] downloading 10 documents in <private>
in the logs it seems to be going round the same loop
2024-07-08 19:32:21.729248+0100 0x105f Error 0x8000000000001a95 429 cloudd: (MMCS) [com.apple.mmcs.default] Pinning failed for <private> on authorizeGetForFiles request.
2024-07-08 19:32:21.734671+0100 0x10a9 Default 0x0 431 nsurlsessiond: (CFNetwork) TIC TCP Conn Cancel [12:0x7fff2846abb0]
2024-07-08 19:32:21.734694+0100 0x10a9 Default 0x0 431 nsurlsessiond: (CFNetwork) TIC TCP [0x7fff2846abb0] completing activity 0x7fff2854f920
2024-07-08 19:32:21.734788+0100 0x10a8 Default 0x0 431 nsurlsessiond: Task 1 for client <private> was cancelled
2024-07-08 19:32:21.736098+0100 0x120d Error 0x0 431 nsurlsessiond: (CFNetwork) NSURLSessionTask finished with error - code: -999
2024-07-08 19:32:21.736129+0100 0x100e Default 0x8000000000001793 143 DuetHeuristic-BM: (DuetActivitySchedulerDaemon) [com.apple.duetactivityscheduler.default] Submitted Activity: <private>
2024-07-08 19:32:21.736363+0100 0x10a9 Error 0x0 431 nsurlsessiond: (CFNetwork) HTTP load failed (error code: -999 [1:89])
2024-07-08 19:32:21.737091+0100 0x105f Error 0x8000000000001a95 429 cloudd: (MMCS) [com.apple.mmcs.default] context 0x7fdf33095d40 received timeout error from NSURLSessionTask but is not marked as cancelled
2024-07-08 19:32:21.737243+0100 0x105f Error 0x8000000000001a95 429 cloudd: (MMCS) [com.apple.mmcs.default] http context 0x7fdf33095d40 did not get a http status, with a 0 byte body.
2024-07-08 19:32:21.737247+0100 0x105f Default 0x8000000000001a95 429 cloudd: (MMCS) [com.apple.mmcs.network.performance] Observed 0.0000 Mbps over 5.6485 seconds for 0 bytes. 0.0254 seconds in queue.
2024-07-08 19:32:21.737478+0100 0x105f Error 0x8000000000001a94 429 cloudd: (MMCS) [com.apple.mmcs.default] itemId:3435 issue com.apple.mmcs/38
2024-07-08 19:32:21.737532+0100 0x105f Error 0x8000000000001a94 429 cloudd: (MMCS) [com.apple.mmcs.default] itemId:3435 issue, com.apple.mmcs/38/NSUnderlyingError com.apple.mmcs/41
2024-07-08 19:32:21.737560+0100 0x105f Error 0x8000000000001a94 429 cloudd: (MMCS) [com.apple.mmcs.default] itemId:3435 issue, com.apple.mmcs/38/NSUnderlyingError, com.apple.mmcs/41/compatibilityCertError com.apple.mmcs/41
2024-07-08 19:32:21.737600+0100 0x105f Error 0x8000000000001a94 429 cloudd: (MMCS) [com.apple.mmcs.default] itemId:3435 issue, com.apple.mmcs/38/NSUnderlyingError, com.apple.mmcs/41/appleCertError com.apple.mmcs/41
iCloud on Sierra 10.12.6 seems to be trying to get the files but then failing due to a certificate pinning error