microsoft-teams-apps-company-communicator: Bot fails to send a message to a user

We are testing our second Company Communicator to smalls groups and found that the bot was unable to send the message to some users.

We have tried sending with the option “Sent in chat to people in teams” and “Sent in chat to members of the following groups” with the same result. We have tried cleaned Teams cache and problem persists.

Version App: Version 5.4.1

The error report is details below:

User ID,UPN,Name,User Type,Delivery Status,Status Reason,Error

3adde888-7b8a-4ce8-hhhhhhhhhhhhh,yyyyyyyyy@xxxxxxx.com, zzzzzzzzzzzzz,Member,Failed,403 : Failed,“Microsoft.Bot.Schema.ErrorResponseException: Operation returned an invalid status code ‘Forbidden’ at Microsoft.Bot.Connector.Conversations.ReplyToActivityWithHttpMessagesAsync(String conversationId, String activityId, Activity activity, Dictionary2 customHeaders, CancellationToken cancellationToken) at Microsoft.Bot.Connector.ConversationsExtensions.ReplyToActivityAsync(IConversations operations, String conversationId, String activityId, Activity activity, CancellationToken cancellationToken) at Microsoft.Bot.Builder.CloudAdapterBase.SendActivitiesAsync(ITurnContext turnContext, Activity[] activities, CancellationToken cancellationToken) at Microsoft.Bot.Builder.TurnContext.<>c__DisplayClass31_0.<<SendActivitiesAsync>g__SendActivitiesThroughAdapter\|1>d.MoveNext() --- End of stack trace from previous location --- at Microsoft.Bot.Builder.TurnContext.SendActivityAsync(IActivity activity, CancellationToken cancellationToken) at Microsoft.Teams.Apps.CompanyCommunicator.Common.Services.Teams.MessageService.<>c__DisplayClass3_1.<<SendMessageAsync>b__1>d.MoveNext() in C:\home\site\repository\Source\CompanyCommunicator.Common\Services\Teams\Messages\MessageService.cs:line 94 --- End of stack trace from previous location --- at Polly.Retry.AsyncRetryEngine.ImplementationAsync[TResult](Func3 action, Context context, CancellationToken cancellationToken, ExceptionPredicates shouldRetryExceptionPredicates, ResultPredicates1 shouldRetryResultPredicates, Func5 onRetryAsync, Int32 permittedRetryCount, IEnumerable1 sleepDurationsEnumerable, Func4 sleepDurationProvider, Boolean continueOnCapturedContext) at Polly.AsyncPolicy.ExecuteAsync[TResult](Func`3 action, Context context, CancellationToken cancellationToken, Boolean continueOnCapturedContext) at Microsoft.Teams.Apps.CompanyCommunicator.Common.Services.Teams.MessageService.<>c__DisplayClass3_0.<<SendMessageAsync>b__0>d.MoveNext() in C:\home\site\repository\Source\CompanyCommunicator.Common\Services\Teams\Messages\MessageService.cs:line 94” df771efa-d816-4af9-9336-xxxxxxxxx,yyyyyyyyy2@zzzzzz.com,xyz ,Member,Succeeded,201 : OK,