Don't add a placeholder option to multiselect widgets

netbox/project-static/js/forms.js

@@ -77,7 +77,9 @@ $(document).ready(function() {
 
         // Wipe out any existing options within the child field and create a default option
         child_field.empty();
-        child_field.append($("<option></option>").attr("value", "").text("---------"));
+        if (!child_field.attr('multiple')) {
+            child_field.append($("<option></option>").attr("value", "").text("---------"));
+        }
 
         if ($(this).val() || $(this).attr('nullable') == 'true') {
             var api_url = child_field.attr('api-url') + '&limit=1000';

netbox/virtualization/forms.py

@@ -140,7 +140,6 @@ class ClusterAddDevicesForm(BootstrapMixin, ChainedFieldsMixin, forms.Form):
             ('rack', 'rack'),
         ),
         label='Device',
-        required=False,
         widget=APISelectMultiple(
             api_url='/api/dcim/devices/?site_id={{site}}&rack_id={{rack}}',
             display_field='display_name',