diff --git a/.last-branch b/.last-branch
index e0b81af..db6f598 100644
--- a/.last-branch
+++ b/.last-branch
@@ -1 +1 @@
-v20260101-12-run-checks-select-all-indeterminate-clear-selection-fix
+v20260101-13-run-checks-select-all-indeterminate-state-fix
diff --git a/containers/backupchecks/src/templates/main/run_checks.html b/containers/backupchecks/src/templates/main/run_checks.html
index b014c3d..2518511 100644
--- a/containers/backupchecks/src/templates/main/run_checks.html
+++ b/containers/backupchecks/src/templates/main/run_checks.html
@@ -381,57 +381,57 @@ function statusClass(status) {
     }
 
     if (selectAll) {
-      function clearAllSelection() {
+      function setAllSelection(checked) {
         var cbs = table.querySelectorAll('tbody .rc_row_cb');
-        cbs.forEach(function (cb) { cb.checked = false; });
-        // Ensure header checkbox is reset as well.
+        cbs.forEach(function (cb) { cb.checked = !!checked; });
+
+        // Keep header checkbox state in sync and avoid a "stuck" indeterminate UI.
         selectAll.indeterminate = false;
-        selectAll.checked = false;
+        selectAll.checked = !!checked;
+
         updateButtons();
       }
 
-      // When the header checkbox is indeterminate (partial selection), users expect a click
-      // to clear the selection, not to select everything.
-      var selectAllWasIndeterminate = false;
-
-      selectAll.addEventListener('mousedown', function () {
-        selectAllWasIndeterminate = !!selectAll.indeterminate;
-      }, true);
-
-      selectAll.addEventListener('click', function (e) {
-        if (selectAllWasIndeterminate) {
+      function toggleHeaderSelection(e) {
+        if (e) {
           e.preventDefault();
           e.stopPropagation();
-          clearAllSelection();
-          selectAllWasIndeterminate = false;
-        }
-      }, true);
-
-      selectAll.addEventListener('keydown', function (e) {
-        // Space toggles checkboxes. If indeterminate, treat Space as "clear selection".
-        if ((e.key === ' ' || e.code === 'Space') && selectAll.indeterminate) {
-          e.preventDefault();
-          e.stopPropagation();
-          clearAllSelection();
-        }
-      }, true);
-
-      selectAll.addEventListener('change', function () {
-        // Safety net: if any browser still fires change after an indeterminate click,
-        // force the expected "clear" behavior.
-        if (selectAllWasIndeterminate) {
-          clearAllSelection();
-          selectAllWasIndeterminate = false;
-          return;
         }
 
         var cbs = table.querySelectorAll('tbody .rc_row_cb');
-        cbs.forEach(function (cb) { cb.checked = selectAll.checked; });
-        updateButtons();
-      });
+        var total = cbs.length;
+        if (!total) {
+          // No rows; always reset header state.
+          selectAll.indeterminate = false;
+          selectAll.checked = false;
+          updateButtons();
+          return;
+        }
+
+        var checked = 0;
+        cbs.forEach(function (cb) { if (cb.checked) checked++; });
+
+        // Behavior:
+        // - none selected => select all
+        // - all selected => clear all
+        // - partial selection (indeterminate) => clear selection
+        var target = (checked === 0);
+
+        setAllSelection(target);
+      }
+
+      // Fully control header checkbox behavior to prevent indeterminate state from getting stuck.
+      selectAll.addEventListener('click', toggleHeaderSelection, true);
+
+      selectAll.addEventListener('keydown', function (e) {
+        // Space/Enter should behave the same as a click.
+        if (e.key === ' ' || e.code === 'Space' || e.key === 'Enter') {
+          toggleHeaderSelection(e);
+        }
+      }, true);
     }
 
-// Prevent browser text selection when using Shift with checkbox selection
+    // Prevent browser text selection when using Shift with checkbox selection
 table.addEventListener('mousedown', function (e) {
   var t = e.target;
   if (!t) return;
diff --git a/docs/changelog.md b/docs/changelog.md
index 20579d4..d6dc80c 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -192,6 +192,15 @@
 - Implemented click interception before the browser toggles the checkbox state to prevent unintended full selection from the indeterminate state.
 - Added consistent keyboard behavior: pressing Space on the indeterminate header checkbox now also clears the selection.
 
+---
+
+## v20260101-13-run-checks-select-all-indeterminate-state-fix
+
+- Fixed the “Select all” checkbox behavior on the Run Checks page.
+- Resolved an issue where the checkbox remained in the indeterminate (`-`) state after clearing the selection.
+- Ensured that after clearing all selected rows, the “Select all” checkbox can again be used to select all rows normally.
+- Improved synchronization between individual row selection and the global “Select all” checkbox state.
+
 ================================================================================================================================================
 ## v0.1.14