The issue you're experiencing is common when using MSAL.NET with Entra ID for Office integration. The problem is that **MSAL.NET authentication doesn't automatically sign you into Office applications** - they use separate authentication flows. Here's how to fix this:

### Root Cause Analysis

[Explanation of the issue]

### Solution 1: Use WAM Broker Integration

[Code example]

### Solution 2: Implement Office-Specific Token Acquisition

[Code example]

### Solution 3: Configure Office-Specific Scopes

[Code example]

### Solution 4: Handle Office Application Integration

[Code example]

### Solution 5: Debugging and Logging

[Code example]

### Key Points:

1. **MSAL.NET and Office use different authentication flows** - Your MSAL authentication doesn't automatically sign into Office

2. **Use WAM broker integration** - Enable proper Windows integration

3. **Office requires specific scopes** - Use the correct Microsoft Graph scopes

4. **Interactive authentication may be needed** - Office might require user interaction

5. **Check account correlation** - Ensure the same account is used for both

This should resolve your Office authentication issues! Let me know if you need help with any specific aspects.