Enhance user MFA method reporting by clarifying sign-in preference handling and adding module dependency checks

Get-UserMfaMethodReport.ps1

@@ -257,17 +257,24 @@ function Get-UserAuthMethodDetail {
         if ($friendly.Category -eq 'Phone') { $hasPhoneMethod = $true }
     }
 
-    # Best-effort default/preferred method. This endpoint reflects the user's
+    # Best-effort default/preferred method. This endpoint only reflects an
-    # own sign-in preference and, unlike the tenant-wide usage/insights report,
+    # explicit override the user (or an admin) has set - unlike the
-    # is not gated behind a P1/P2 license - but treat failures as "unknown"
+    # tenant-wide usage/insights report, it's not gated behind a P1/P2
-    # rather than fatal, since behavior can vary by tenant/SDK version.
+    # license - but treat failures as "unknown" rather than fatal, since
+    # behavior can vary by tenant/SDK version. Deliberately NOT guessed/
+    # inferred when unavailable: Entra ID's actual method selection (e.g.
+    # under System-preferred MFA) depends on per-user state this API doesn't
+    # expose, so a guess here can be flatly wrong and is worse than admitting
+    # it's unknown - this value drives real remediation decisions.
     $defaultMethod = $null
     try {
         $preference = Get-MgBetaUserAuthenticationSignInPreference -UserId $UserId -ErrorAction Stop
+        if ($preference.UserPreferredMethodForSecondaryAuthentication -and $preference.UserPreferredMethodForSecondaryAuthentication -ne 'none') {
             $defaultMethod = $preference.UserPreferredMethodForSecondaryAuthentication
         }
+    }
     catch {
-        Write-Verbose "No sign-in preference available for user '$UserId' (falling back to heuristic): $_"
+        Write-Warning "No sign-in preference available for user '$UserId': $_"
     }
 
     return [PSCustomObject]@{
@@ -403,6 +410,25 @@ $($methodRows -join "`n")
 
 # --- Main --------------------------------------------------------------
 try {
+    # Fail fast and loudly if a module this script depends on isn't
+    # installed OR can't actually be loaded (e.g. an assembly-version
+    # conflict with another installed Microsoft.Graph module version),
+    # rather than letting every per-user call into it fail silently later
+    # and produce an incomplete/misleading report. Microsoft.Graph.Beta.
+    # Identity.SignIns provides Get-MgBetaUserAuthenticationSignInPreference,
+    # which reads each user's actual default sign-in method - there is no
+    # v1.0/GA equivalent, this data is beta-only in Microsoft Graph.
+    $requiredBetaModule = 'Microsoft.Graph.Beta.Identity.SignIns'
+    if (-not (Get-Module -ListAvailable -Name $requiredBetaModule)) {
+        throw "Required module '$requiredBetaModule' is not installed. It's needed to read each user's actual default sign-in method. Install it with: Install-Module $requiredBetaModule -Scope CurrentUser"
+    }
+    try {
+        Import-Module -Name $requiredBetaModule -ErrorAction Stop
+    }
+    catch {
+        throw "Required module '$requiredBetaModule' is installed but failed to load - this is usually caused by multiple mismatched Microsoft.Graph module versions installed side by side (an assembly-version conflict), not a missing module. Run: Get-Module -ListAvailable 'Microsoft.Graph*' | Group-Object Name | Where-Object { (`$_.Group.Version | Sort-Object -Unique).Count -gt 1 } to find the mismatched ones, update them all to the same version, and remove the old ones. Underlying error: $_"
+    }
+
     Write-Verbose 'Connecting to Microsoft Graph...'
     $requiredScopes = @(
         'User.Read.All'
@@ -473,7 +499,13 @@ try {
                 $_ -notin @('mobilePhone', 'alternateMobilePhone', 'officePhone', 'email', 'password')
             }
             $hasStrongMethod = [bool]$strongRegistered
+            # This report field is also "none" (a literal string, not $null)
+            # for users without an explicit override - most commonly because
+            # the tenant runs System-preferred MFA. Normalize it so the
+            # fallback heuristic below actually kicks in instead of the row
+            # showing the literal word "none" as if it were a real method.
             $defaultMethod = $regDetail.UserPreferredMethodForSecondaryAuthentication
+            if ($defaultMethod -eq 'none') { $defaultMethod = $null }
         }
         else {
             # Fallback path: per-user methods API, works without P1/P2.