fix(assignments): use bulk /assign endpoint for removals on all types

Settings Catalog and other bulk-assign types do not support DELETE on
individual assignments. Removal now reloads existing assignments,
filters out selected targets, sanitizes remaining payloads, and
re-POSTs to <API>/<id>/assign. This mirrors the add flow and works
universally across all supported object types.

Scripts/Bulk-AssignmentManager.ps1

@@ -648,6 +648,29 @@ elseif($action -eq "Remove assignments")
         exit 0
     }
 
+    # Helper: compute TargetDesc for an assignment
+    function Get-AssignmentTargetDesc
+    {
+        param($Ass)
+        $tt = $Ass.target."@odata.type"
+        switch($tt)
+        {
+            "#microsoft.graph.groupAssignmentTarget"
+            {
+                $grp = $groups | Where-Object { $_.id -eq $Ass.target.groupId } | Select-Object -First 1
+                return "Include: $(if($grp){$grp.displayName}else{$Ass.target.groupId})"
+            }
+            "#microsoft.graph.exclusionGroupAssignmentTarget"
+            {
+                $grp = $groups | Where-Object { $_.id -eq $Ass.target.groupId } | Select-Object -First 1
+                return "Exclude: $(if($grp){$grp.displayName}else{$Ass.target.groupId})"
+            }
+            "#microsoft.graph.allLicensedUsersAssignmentTarget" { return "All Users" }
+            "#microsoft.graph.allDevicesAssignmentTarget"       { return "All Devices" }
+            default { return "Unknown" }
+        }
+    }
+
     # Execute
     $success = 0
     $failed = 0
@@ -657,15 +680,42 @@ elseif($action -eq "Remove assignments")
         if($objAssignments.Count -eq 0) { continue }
 
         Write-Host "`nProcessing: $($obj."$($objectType.NameProp)")" -ForegroundColor Cyan
-        foreach($ass in $objAssignments)
+        try
         {
-            try
+            $existing = Invoke-GraphRequest "$($objectType.API)/$($obj.id)/assignments"
+            $remaining = @()
+            foreach($ea in $existing.value)
+            {
+                $desc = Get-AssignmentTargetDesc -Ass $ea
+                if($desc -in $selectedTargetDisplays)
+                {
+                    continue
+                }
+                # Sanitize for re-post
+                $clean = $ea | ConvertTo-Json -Depth 50 | ConvertFrom-Json
+                if($clean.PSObject.Properties["id"])     { $clean.PSObject.Properties.Remove("id") }
+                if($clean.PSObject.Properties["source"]) { $clean.PSObject.Properties.Remove("source") }
+                if(-not $clean."@odata.type")
+                {
+                    $clean | Add-Member -NotePropertyName "@odata.type" -NotePropertyValue $objectType.AssignmentODataType -Force
+                }
+                $remaining += $clean
+            }
+
+            $assignPayload = @{
+                $objectType.AssignmentsType = $remaining
+            } | ConvertTo-Json -Depth 50 -Compress
+
+            $null = Invoke-GraphRequest "$($objectType.API)/$($obj.id)/assign" -HttpMethod POST -Content $assignPayload
+            foreach($ass in $objAssignments)
             {
-                $null = Invoke-GraphRequest "$($objectType.API)/$($obj.id)/assignments/$($ass.AssignmentId)" -HttpMethod DELETE
                 Write-Host "  OK: Removed $($ass.TargetDesc)" -ForegroundColor Green
                 $success++
             }
-            catch
+        }
+        catch
+        {
+            foreach($ass in $objAssignments)
             {
                 Write-Host "  ERROR: Failed to remove $($ass.TargetDesc). $($_.Exception.Message)" -ForegroundColor Red
                 $failed++