Outlook --> Google Calendar sync returning spoadic 400s

[brianabauman]

On version 4.4.1.0, I'm experiencing sporadic failures to sync my calendar with Google. The error message is:

<SynchronizationReport xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <ProfileName><MY_COMPANY_NAME></ProfileName>
  <ProfileId>5174bc99-e361-44fd-a5ad-9517c2e26329</ProfileId>
  <StartTime>2023-08-30T15:56:03.1853703Z</StartTime>
  <ADelta>Unchanged: 39 , Added: 0 , Deleted 0 ,  Changed 1</ADelta>
  <BDelta>Unchanged: 39 , Added: 0 , Deleted 1 ,  Changed 0</BDelta>
  <AJobsInfo>Create 0 , Update 0 , Delete 0</AJobsInfo>
  <BJobsInfo>Create 1 , Update 1 , Delete 0</BJobsInfo>
  <LoadErrors />
  <EntitySynchronizationReports>
    <EntitySynchronizationReport>
      <MappingErrors />
      <MappingWarnings />
      <AId>00000000BF52EF0EAEA5B240972DCDB6CACC5C110700DA1624C5EA18C4448BB5F95F36652FC900000D5A0FA4000002965CE105254646BC89ED4CF2BB63960000B43680520000</AId>
      <BId>/caldav/v2/b<MY_EMAIL_ADDRESS>/events/140abdee-3deb-4f7b-b2a5-a1d8a213d13f.ics</BId>
      <ExceptionThatLeadToAbortion>CalDavSynchronizer.DataAccess.WebDavClientException: Response status code does not indicate success: '400' ('Bad Request'). Message:
&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;D:error xmlns:D="DAV:"/&gt;

   at CalDavSynchronizer.DataAccess.HttpClientBasedClient.WebDavClient.&lt;EnsureSuccessStatusCode&gt;d__10.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)
   at CalDavSynchronizer.DataAccess.HttpClientBasedClient.WebDavClient.&lt;ExecuteWebDavRequest&gt;d__9.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at CalDavSynchronizer.DataAccess.HttpClientBasedClient.WebDavClient.&lt;ExecuteWebDavRequestAndReturnResponseHeaders&gt;d__8.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at CalDavSynchronizer.DataAccess.CalDavDataAccess.&lt;TryUpdateEntity&gt;d__28.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at CalDavSynchronizer.Implementation.CalDavRepository`1.&lt;TryUpdate&gt;d__16.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at CalDavSynchronizer.Implementation.CalDavRepository`1.&lt;TryUpdate&gt;d__16.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)
   at GenSync.EntityRepositories.BatchEntityRepositoryAdapter`4.&lt;PerformOperations&gt;d__3.MoveNext()</ExceptionThatLeadToAbortion>
      <Operation>UpdateInB</Operation>
    </EntitySynchronizationReport>
  </EntitySynchronizationReports>
  <ConsiderExceptionThatLeadToAbortionAsWarning>false</ConsiderExceptionThatLeadToAbortionAsWarning>
  <Duration>00:00:01.5034520</Duration>
</SynchronizationReport>

Did anything change on Google's API? The issue is sporadic -- it's not clear why some syncs fail. What other debugging information can I provide?