diff --git a/src/ert/gui/simulation/multiple_data_assimilation_panel.py b/src/ert/gui/simulation/multiple_data_assimilation_panel.py
index d9a154fe5fa..5e550b41951 100644
--- a/src/ert/gui/simulation/multiple_data_assimilation_panel.py
+++ b/src/ert/gui/simulation/multiple_data_assimilation_panel.py
@@ -103,9 +103,9 @@ def __init__(
             self._active_realizations_model,  # type: ignore
             "config/simulation/active_realizations",
         )
+        self._active_realizations_field.setObjectName("active_realizations_box")
         self._active_realizations_field.setValidator(RangeStringArgument(ensemble_size))
         self._ensemble_selector = EnsembleSelector(notifier)
-        self._realizations_from_fs()
         layout.addRow("Active realizations:", self._active_realizations_field)
 
         self._restart_box = QCheckBox("")
@@ -114,6 +114,7 @@ def __init__(
         self._restart_box.toggled.connect(self.update_experiment_edit)
 
         self._restart_box.setEnabled(bool(self._ensemble_selector._ensemble_list()))
+        self._ensemble_selector.setEnabled(False)
         layout.addRow("Restart run:", self._restart_box)
 
         self._ensemble_selector.ensemble_populated.connect(self.restart_run_toggled)
@@ -189,6 +190,11 @@ def restart_run_toggled(self) -> None:
             if self._restart_box.isChecked()
             else MultipleDataAssimilation.default_weights
         )
+        if self._restart_box.isChecked():
+            self._realizations_from_fs()
+        else:
+            # If box is unchecked we reset to the default mask
+            self._active_realizations_field.model.setValue(value="")
 
     def _createInputForWeights(self, layout: QFormLayout) -> None:
         relative_iteration_weights_model = ValueModel(self.weights)
diff --git a/tests/ert/ui_tests/gui/test_restart_esmda.py b/tests/ert/ui_tests/gui/test_restart_esmda.py
index 05723301520..6c7c8e312ed 100644
--- a/tests/ert/ui_tests/gui/test_restart_esmda.py
+++ b/tests/ert/ui_tests/gui/test_restart_esmda.py
@@ -4,7 +4,7 @@
 from ert.gui.ertwidgets import StringBox
 from ert.gui.simulation.experiment_panel import ExperimentPanel
 from ert.gui.simulation.run_dialog import RunDialog
-from ert.run_models import MultipleDataAssimilation
+from ert.run_models import MultipleDataAssimilation, SingleTestRun
 
 from .conftest import get_child
 
@@ -40,6 +40,44 @@ def test_restart_esmda(ensemble_experiment_has_run_no_failure, qtbot):
     )
 
 
+def test_active_realizations_esmda(opened_main_window_poly, qtbot):
+    """This runs a single test run and then verifies that this does
+    not interfere with the activate realizations in the es_mda panel
+    unless the restart from that specific ensemble is checked.
+    """
+    gui = opened_main_window_poly
+
+    experiment_panel = get_child(gui, ExperimentPanel)
+    simulation_mode_combo = get_child(experiment_panel, QComboBox)
+    simulation_mode_combo.setCurrentText(SingleTestRun.name())
+
+    single_test_run_panel = gui.findChild(QWidget, name="Single_test_run_panel")
+    assert single_test_run_panel
+    run_experiment = experiment_panel.findChild(QWidget, name="run_experiment")
+    qtbot.mouseClick(run_experiment, Qt.MouseButton.LeftButton)
+    qtbot.waitUntil(lambda: gui.findChild(RunDialog) is not None)
+    run_dialog = gui.findChild(RunDialog)
+    qtbot.waitUntil(lambda: run_dialog.is_simulation_done() == True, timeout=15000)
+    assert (
+        run_dialog._total_progress_label.text()
+        == "Total progress 100% — Experiment completed."
+    )
+
+    simulation_mode_combo.setCurrentText(MultipleDataAssimilation.name())
+    es_mda_panel = gui.findChild(QWidget, name="ES_MDA_panel")
+    assert es_mda_panel
+    active_reals = gui.findChild(StringBox, "active_realizations_box")
+    assert active_reals.text() == "0-19"
+
+    restart_checkbox = es_mda_panel.findChild(QCheckBox, name="restart_checkbox_esmda")
+    assert restart_checkbox
+    assert not restart_checkbox.isChecked()
+    restart_checkbox.click()
+    assert active_reals.text() == "0"
+    restart_checkbox.click()
+    assert active_reals.text() == "0-19"
+
+
 def test_custom_weights_stored_and_retrieved_from_metadata_esmda(
     opened_main_window_minimal_realizations, qtbot
 ):