diff --git a/src/Mod/Assembly/JointObject.py b/src/Mod/Assembly/JointObject.py
index d4a1a3964f..4a14a84f92 100644
--- a/src/Mod/Assembly/JointObject.py
+++ b/src/Mod/Assembly/JointObject.py
@@ -1813,8 +1813,8 @@ class TaskAssemblyCreateJoint(QtCore.QObject):
             try:
                 # Use a set to handle cases where both refs point to the same object
                 parts_to_isolate = {
-                    UtilsAssembly.getObject(self.refs[0]),
-                    UtilsAssembly.getObject(self.refs[1]),
+                    self.getMovingPart(self.refs[0]),
+                    self.getMovingPart(self.refs[1]),
                 }
                 assembly_vobj.isolateComponents(list(parts_to_isolate), isolate_mode)
             except Exception as e: