diff --git a/MantidQt/CustomInterfaces/inc/MantidQtCustomInterfaces/Muon/MuonAnalysisDataLoader.h b/MantidQt/CustomInterfaces/inc/MantidQtCustomInterfaces/Muon/MuonAnalysisDataLoader.h
index 5c0c23eacc11..facb4860a384 100644
--- a/MantidQt/CustomInterfaces/inc/MantidQtCustomInterfaces/Muon/MuonAnalysisDataLoader.h
+++ b/MantidQt/CustomInterfaces/inc/MantidQtCustomInterfaces/Muon/MuonAnalysisDataLoader.h
@@ -95,6 +95,8 @@ class MANTIDQT_CUSTOMINTERFACES_DLL MuonAnalysisDataLoader {
   /// Load dead times from file
   Mantid::API::Workspace_sptr
   loadDeadTimesFromFile(const std::string &filename) const;
+  // empty the cache
+  void clearCache();
 
 protected:
   /// Set properties of algorithm from options
diff --git a/MantidQt/CustomInterfaces/src/Muon/MuonAnalysis.cpp b/MantidQt/CustomInterfaces/src/Muon/MuonAnalysis.cpp
index b4dd30338ab2..5001f39717e9 100644
--- a/MantidQt/CustomInterfaces/src/Muon/MuonAnalysis.cpp
+++ b/MantidQt/CustomInterfaces/src/Muon/MuonAnalysis.cpp
@@ -2694,7 +2694,7 @@ void MuonAnalysis::doSetToolbarsHidden(bool hidden) {
  */
 void MuonAnalysis::onDeadTimeTypeChanged(int choice) {
   m_deadTimesChanged = true;
-
+  m_dataLoader.clearCache();
   if (choice == 0 || choice == 1) // if choice == none || choice == from file
   {
     m_uiForm.mwRunDeadTimeFile->setVisible(false);
@@ -2757,6 +2757,7 @@ void MuonAnalysis::deadTimeFileSelected() {
  * from the form
  */
 void MuonAnalysis::setTimeZeroState(int checkBoxState) {
+  m_dataLoader.clearCache();
   if (checkBoxState == -1)
     checkBoxState = m_uiForm.timeZeroAuto->checkState();
 
@@ -2778,6 +2779,7 @@ void MuonAnalysis::setTimeZeroState(int checkBoxState) {
  * from the form
  */
 void MuonAnalysis::setFirstGoodDataState(int checkBoxState) {
+  m_dataLoader.clearCache();
   if (checkBoxState == -1)
     checkBoxState = m_uiForm.firstGoodDataAuto->checkState();
 
diff --git a/MantidQt/CustomInterfaces/src/Muon/MuonAnalysisDataLoader.cpp b/MantidQt/CustomInterfaces/src/Muon/MuonAnalysisDataLoader.cpp
index c8c5914ab134..7ce7bebaa575 100644
--- a/MantidQt/CustomInterfaces/src/Muon/MuonAnalysisDataLoader.cpp
+++ b/MantidQt/CustomInterfaces/src/Muon/MuonAnalysisDataLoader.cpp
@@ -472,5 +472,11 @@ void MuonAnalysisDataLoader::updateCache() const {
   }
 }
 
+void MuonAnalysisDataLoader::clearCache() {
+  if (!m_loadedDataCache.empty()) {
+    m_loadedDataCache.clear();
+  }
+}
+
 } // namespace CustomInterfaces
 } // namespace MantidQt
diff --git a/docs/source/release/v3.9.1/index.rst b/docs/source/release/v3.9.1/index.rst
index 3e3df80e6caa..bad57dbcd62a 100644
--- a/docs/source/release/v3.9.1/index.rst
+++ b/docs/source/release/v3.9.1/index.rst
@@ -37,7 +37,9 @@ Changes in this version
 * `18915 <https://www.github.com/mantidproject/mantid/pull/18915>`_ Add missing parameter in function call in performance test
 * `18926 <https://www.github.com/mantidproject/mantid/pull/18926>`_ Fix wrong detector selection when loading high angle bank user files in ISIS SANS
 * `18927 <https://www.github.com/mantidproject/mantid/pull/18927>`_ Fix sum file behaviour for vesuvio diffraction
+* `18955 <https://www.github.com/mantidproject/mantid/pull/18955>`_ Fix crash in MonitorDlg
 * `18959 <https://www.github.com/mantidproject/mantid/pull/18959>`_ Blank instrument view with U correction
+* `18972 <https://www.github.com/mantidproject/mantid/pull/18972>`_ Fix reading dead time data in Muon interface
 
 Summary of impact
 -----------------
@@ -72,9 +74,12 @@ Summary of impact
 +-------+-----------------------------------------------------------------------------------+---------------------------------------------+--------------+
 | 18927 | Allow Vesuvio to sum runs in diffraction reduction                                | Fix incorrect assignment in loop            | **low**      |
 +-------+-----------------------------------------------------------------------------------+---------------------------------------------+--------------+
+| 18955 | Avoid possible crash in algorithm monitor dialog                                  | Check for null pointer                      | **low**      |
++-------+-----------------------------------------------------------------------------------+---------------------------------------------+--------------+
 | 18959 | Fixes blank view when U correction applied                                        | Fix missing call after #18875               | **medium**   |
 +-------+-----------------------------------------------------------------------------------+---------------------------------------------+--------------+
-
+| 18972 | Loads data with/without dead-time correction as per user request                  | Clear data cache after option is updated    | **low**      |
++-------+-----------------------------------------------------------------------------------+---------------------------------------------+--------------+
 
 .. _download page: http://download.mantidproject.org