Index: sources/gui/qml/pages/pretreatment/PreTreatmentBase.qml
===================================================================
diff -u -r1286d74bd015276aab604808be2766136091c125 -rc70815ad2b3beadf61832f2e4d12eb90d476e020
--- sources/gui/qml/pages/pretreatment/PreTreatmentBase.qml	(.../PreTreatmentBase.qml)	(revision 1286d74bd015276aab604808be2766136091c125)
+++ sources/gui/qml/pages/pretreatment/PreTreatmentBase.qml	(.../PreTreatmentBase.qml)	(revision c70815ad2b3beadf61832f2e4d12eb90d476e020)
@@ -26,25 +26,22 @@
  * \brief   the parent page of the pre-treatment screens
  */
 TreatmentFlowBase { id: _root
-    objectName: "_PreTreatmentBase"
-    header.visible  : false
-    headerTitle     : qsTr("Setup Treatment")
+    objectName              : "_PreTreatmentBase"
+    header.visible          : false
+    headerTitle             : qsTr("Setup Treatment")
 
-    onVisibleChanged: if ( visible ) { _root.updateModel() }
+    onVisibleChanged: if ( visible && instructionBased ) { _root.updateModel() }
 
     // update model for instruction based steps
     function updateModel () {
-        let  stepName = stepNames[stackStepIndex]
-        if ( stepName === undefined ) stepName = ""
+        let  stepName           = stepNames[stackStepIndex] ?? ""
+        let group               = vSettings.groupFormat(stepName, vSettings.advancedMode || _root.subStepName.length === 0 ? "" : _root.subStepName )
+        let instructionsGroup   = vSettings.instructions[group]
 
-        let group = vSettings.groupFormat(stepName, vSettings.advancedMode || _root.subStepName.length === 0 ? "" : _root.subStepName )
+        if ( ! instructionsGroup ) { return }
 
-        let instructionsGroup    = vSettings.instructions[group]
-
-        if ( instructionsGroup !== undefined ) {
-            instructionTitle      = instructionsGroup.title
-            instructionStepNames  = instructionsGroup.keys
-            instructionStepImages = instructionsGroup.values
-        }
+        instructionTitle      = instructionsGroup.title
+        instructionStepNames  = instructionsGroup.keys
+        instructionStepImages = instructionsGroup.values
     }
 }