Why Do Cmdlet and Microsoft Graph API Responses for Working Hours and WorkDays Depend on the Source of Last Modification?

Question

I noticed an unusual behavior when retrieving a user's working hours using Microsoft Graph API or PowerShell cmdlets:

Behavior Observed:

Dependency on Last Modification Source:

1. If the working hours were last modified in Viva Insights, the responses reflect changes made in Viva Insights.
2. If the working hours were last modified in Outlook, the responses are based on the working hours set in Outlook.

One-Way Synchronization:

1. When working hours are modified in Outlook, these changes are synchronized and reflected in services like Viva Insights.
2. However, if the working hours are updated in Viva Insights (or other external services), the changes are not synchronized back to Outlook, but the responses from the Microsoft Graph API or cmdlets still reflect these updated values.

API/Command Used:

I have used the following methods to fetch working hours:

Microsoft Graph API

GET https://graph.microsoft.com/v1.0/me/mailboxSettings

This returns the workingHours property but does not indicate the source of the data.

PowerShell Cmdlet

Get-MailboxCalendarConfiguration

Provides general settings like time zone and working hours but no granular details about day-wise variations or the source of data.

Questions:

1. Why does the response depend on the source of the last modification (e.g., Outlook vs. Viva Insights)?

2. Is there a way to enforce consistency across services, ensuring synchronization of changes made in Viva Insights back to Outlook?

3. Is there a method to explicitly determine the source of the data (e.g., whether it reflects changes from Outlook, Viva Insights, or elsewhere)?

This behavior creates confusion when managing working hours across multiple services. Any insights or suggestions would be greatly appreciated!