diff --git a/src/backend/InvenTree/report/api.py b/src/backend/InvenTree/report/api.py
index d710359b51..1782d95ed9 100644
--- a/src/backend/InvenTree/report/api.py
+++ b/src/backend/InvenTree/report/api.py
@@ -150,7 +150,7 @@ class LabelPrint(GenericAPIView):
         """Return the plugin class for the given plugin key."""
         from plugin.models import PluginConfig
 
-        if plugin_slug is None:
+        if not plugin_slug:
             # Use the default label printing plugin
             plugin_slug = InvenTreeLabelPlugin.NAME.lower()
 
@@ -196,10 +196,10 @@ class LabelPrint(GenericAPIView):
 
         # Plugin information provided?
         if self.request:
-            plugin_key = self.request.data.get('plugin', None)
+            plugin_key = self.request.data.get('plugin', '')
             # Legacy url based lookup
             if not plugin_key:
-                plugin_key = self.request.query_params.get('plugin', None)
+                plugin_key = self.request.query_params.get('plugin', '')
             plugin = self.get_plugin_class(plugin_key)
             plugin_serializer = self.get_plugin_serializer(plugin)
 
diff --git a/src/backend/InvenTree/templates/js/translated/forms.js b/src/backend/InvenTree/templates/js/translated/forms.js
index dd187dc829..56ae5a2c3c 100644
--- a/src/backend/InvenTree/templates/js/translated/forms.js
+++ b/src/backend/InvenTree/templates/js/translated/forms.js
@@ -2030,7 +2030,7 @@ function initializeRelatedField(field, fields, options={}) {
 
                 // Each 'row' must have the 'id' attribute
                 for (var idx = 0; idx < data.length; idx++) {
-                    data[idx].id = data[idx].pk;
+                    data[idx].id = data[idx][field.pk_field ?? 'pk'];
                 }
 
                 // Ref: https://select2.org/data-sources/formats
@@ -2054,7 +2054,9 @@ function initializeRelatedField(field, fields, options={}) {
                 data = item.element.instance;
             }
 
-            if (!data.pk) {
+            const pkField = field.pk_field ?? 'pk';
+
+            if (!data[pkField]) {
                 return $(searching());
             }
 
@@ -2075,6 +2077,8 @@ function initializeRelatedField(field, fields, options={}) {
             // Or, use the raw 'item' data as a backup
             var data = item;
 
+            const pkField = field.pk_field ?? 'pk';
+
             if (item.element && item.element.instance) {
                 data = item.element.instance;
             }
@@ -2084,7 +2088,7 @@ function initializeRelatedField(field, fields, options={}) {
                 field.onSelect(data, field, options);
             }
 
-            if (!data.pk) {
+            if (!data[pkField]) {
                 return field.placeholder || '';
             }
 
@@ -2246,7 +2250,9 @@ function setRelatedFieldData(name, data, options={}) {
 
     var select = getFormFieldElement(name, options);
 
-    var option = new Option(name, data.pk, true, true);
+    const pkField = options?.fields[name]?.pk_field ?? 'pk';
+
+    var option = new Option(name, data[pkField], true, true);
 
     // Assign the JSON data to the 'instance' attribute,
     // so we can access and render it later
diff --git a/src/backend/InvenTree/templates/js/translated/label.js b/src/backend/InvenTree/templates/js/translated/label.js
index 0366f5b8b1..fff34aecf6 100644
--- a/src/backend/InvenTree/templates/js/translated/label.js
+++ b/src/backend/InvenTree/templates/js/translated/label.js
@@ -48,7 +48,7 @@ const defaultLabelTemplates = {
  */
 function printLabels(options) {
 
-    let pluginId = -1;
+    let plugin_name = '';
 
     if (!options.items || options.items.length == 0) {
         showAlertDialog(
@@ -67,14 +67,13 @@ function printLabels(options) {
         items: item_string,
     };
 
-    function getPrintingFields(plugin_id, callback) {
-        let url = '{% url "api-label-print" %}' + `?plugin=${plugin_id}`;
+    function getPrintingFields(plugin_slug, callback) {
+
+        let url = '{% url "api-label-print" %}' + `?plugin=${plugin_slug}`;
 
         inventreeGet(
             url,
-            {
-                plugin: plugin_id,
-            },
+            {},
             {
                 method: 'OPTIONS',
                 success: function(response) {
@@ -88,11 +87,11 @@ function printLabels(options) {
     // Callback when a particular label printing plugin is selected
     function onPluginSelected(value, name, field, formOptions) {
 
-        if (value == pluginId) {
+        if (value == plugin_name) {
             return;
         }
 
-        pluginId = value;
+        plugin_name = value;
 
         // Request new printing options for the selected plugin
         getPrintingFields(value, function(fields) {
@@ -108,7 +107,9 @@ function printLabels(options) {
 
     const baseFields = {
         template: {},
-        plugin: {},
+        plugin: {
+            idField: 'key',
+        },
         items: {}
     };