The defaultValueExpression doesn't work for fields placed within a Dy…

src/question.ts

@@ -2080,7 +2080,9 @@ export class Question extends SurveyElement<Question>
       newValue = this.valueFromDataCallback(newValue);
     }
     if(!this.checkIsValueCorrect(newValue)) return;
+    this.isChangingViaDefaultValue = true;
     this.setQuestionValue(this.valueFromData(newValue));
+    this.isChangingViaDefaultValue = false;
     this.updateDependedQuestions();
     this.updateIsAnswered();
   }

tests/question_paneldynamic_tests.ts

@@ -6133,3 +6133,57 @@ QUnit.test("nested panel.panelCount&expression question", function (assert) {
   const panel1 = rootPanel.panels[0].getQuestionByName("panel2");
   assert.equal(panel1.panels.length, 3, "It should be 3 panels");
 });
+QUnit.test("nested panel.panelCount&expression question", function (assert) {
+  const survey = new SurveyModel({
+    "elements": [
+      {
+        "type": "paneldynamic",
+        "name": "panel1",
+        "valueName": "shared",
+        "templateElements": [
+          {
+            "type": "text",
+            "name": "A"
+          }
+        ],
+        "panelCount": 1
+      },
+      {
+        "type": "paneldynamic",
+        "name": "panel2",
+        "valueName": "shared",
+        "templateElements": [
+          {
+            "type": "text",
+            "name": "B"
+          },
+          {
+            "type": "text",
+            "name": "C",
+            "defaultValueExpression": "{panel.A}",
+            "readOnly": true
+          },
+          {
+            "type": "text",
+            "name": "D",
+            "defaultValueExpression": "{panel.B}+{panel.C}",
+            "readOnly": true
+          },
+          {
+            "type": "expression",
+            "name": "E",
+            "expression": "{panel.B}+{panel.C}"
+          }
+        ]
+      }
+    ]
+  });
+  const panel1 = <QuestionPanelDynamicModel>survey.getQuestionByName("panel1");
+  panel1.panels[0].getQuestionByName("A").value = 1;
+  const panel2 = <QuestionPanelDynamicModel>survey.getQuestionByName("panel2");
+  const panel = panel2.panels[0];
+  panel.getQuestionByName("B").value = 2;
+  assert.equal(panel.getQuestionByName("C").value, 1, "C");
+  assert.equal(panel.getQuestionByName("D").value, 3, "D");
+  assert.equal(panel.getQuestionByName("E").value, 3, "E");
+});