Index: sources/gui/qml/pages/pretreatment/PreTreatmentBase.qml
===================================================================
diff -u -r1286d74bd015276aab604808be2766136091c125 -rf90366dd7a36ac03a4e387550811fe5b8a7fbe80
--- sources/gui/qml/pages/pretreatment/PreTreatmentBase.qml	(.../PreTreatmentBase.qml)	(revision 1286d74bd015276aab604808be2766136091c125)
+++ sources/gui/qml/pages/pretreatment/PreTreatmentBase.qml	(.../PreTreatmentBase.qml)	(revision f90366dd7a36ac03a4e387550811fe5b8a7fbe80)
@@ -30,21 +30,18 @@
     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
     }
 }