diff --git a/polygerrit-ui/app/constants/reporting.ts b/polygerrit-ui/app/constants/reporting.ts
index 239c6ee..325787f 100644
--- a/polygerrit-ui/app/constants/reporting.ts
+++ b/polygerrit-ui/app/constants/reporting.ts
@@ -128,4 +128,11 @@
   COMMENTS_AUTOCLOSE_CHECKS_UPDATED = 'comments-autoclose-checks-updated',
   COMMENTS_AUTOCLOSE_THREADS_UPDATED = 'comments-autoclose-threads-updated',
   COMMENTS_AUTOCLOSE_COMMENT_REMOVED = 'comments-autoclose-comment-removed',
+  // The following interactions are logged for investigating a spurious bug of
+  // auto-closing diffs.
+  DIFF_AUTOCLOSE_DIFF_UNDEFINED = 'diff-autoclose-diff-undefined',
+  DIFF_AUTOCLOSE_DIFF_ONGOING = 'diff-autoclose-diff-ongoing',
+  DIFF_AUTOCLOSE_RELOAD_ON_WHITESPACE = 'diff-autoclose-reload-on-whitespace',
+  DIFF_AUTOCLOSE_RELOAD_ON_SYNTAX = 'diff-autoclose-reload-on-syntax',
+  DIFF_AUTOCLOSE_RELOAD_FILELIST_PREFS = 'diff-autoclose-reload-filelist-prefs',
 }
diff --git a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.ts b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.ts
index 88255b7..b04c63f 100644
--- a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.ts
+++ b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.ts
@@ -60,7 +60,7 @@
 import {GrCursorManager} from '../../shared/gr-cursor-manager/gr-cursor-manager';
 import {ChangeComments} from '../../diff/gr-comment-api/gr-comment-api';
 import {ParsedChangeInfo, PatchSetFile} from '../../../types/types';
-import {Timing} from '../../../constants/reporting';
+import {Interaction, Timing} from '../../../constants/reporting';
 import {RevisionInfo} from '../../shared/revision-info/revision-info';
 import {select} from '../../../utils/observable-util';
 import {resolve} from '../../../models/dependency';
@@ -1598,6 +1598,10 @@
     if (!this.diffs.length) {
       return;
     }
+    this.reporting.reportInteraction(
+      Interaction.DIFF_AUTOCLOSE_RELOAD_FILELIST_PREFS
+    );
+
     // Re-render all expanded diffs sequentially.
     this.renderInOrder(this.expandedFiles, this.diffs);
   }
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.ts b/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.ts
index 71f596f..b890f21 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.ts
+++ b/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.ts
@@ -563,6 +563,9 @@
     return this.reloadPromise;
   }
 
+  // for DIFF_AUTOCLOSE logging purposes only
+  private reloadOngoing = false;
+
   async reloadInternal(shouldReportMetric?: boolean) {
     this.reporting.time(Timing.DIFF_TOTAL);
     this.reporting.time(Timing.DIFF_LOAD);
@@ -572,6 +575,10 @@
     this.diff = undefined;
     this.errorMessage = null;
     const whitespaceLevel = this.getIgnoreWhitespace();
+    if (this.reloadOngoing) {
+      this.reporting.reportInteraction(Interaction.DIFF_AUTOCLOSE_DIFF_ONGOING);
+    }
+    this.reloadOngoing = true;
 
     try {
       // We are carefully orchestrating operations that have to wait for another
@@ -581,6 +588,11 @@
       // assets in parallel.
       const layerPromise = this.initLayers();
       const diff = await this.getDiff();
+      if (diff === undefined) {
+        this.reporting.reportInteraction(
+          Interaction.DIFF_AUTOCLOSE_DIFF_UNDEFINED
+        );
+      }
       this.loadedWhitespaceLevel = whitespaceLevel;
       this.reportDiff(diff);
 
@@ -623,6 +635,7 @@
       }
     } finally {
       this.reporting.timeEnd(Timing.DIFF_TOTAL, this.timingDetails());
+      this.reloadOngoing = false;
     }
   }
 
@@ -1362,6 +1375,9 @@
       preferredWhitespaceLevel !== loadedWhitespaceLevel &&
       !noRenderOnPrefsChange
     ) {
+      this.reporting.reportInteraction(
+        Interaction.DIFF_AUTOCLOSE_RELOAD_ON_WHITESPACE
+      );
       return this.reload();
     }
   }
@@ -1380,6 +1396,9 @@
     if (oldPrefs?.syntax_highlighting === prefs.syntax_highlighting) return;
 
     if (!noRenderOnPrefsChange) {
+      this.reporting.reportInteraction(
+        Interaction.DIFF_AUTOCLOSE_RELOAD_ON_SYNTAX
+      );
       return this.reload();
     }
   }
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host_test.ts b/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host_test.ts
index bb7ffe0..95ac40f 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host_test.ts
+++ b/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host_test.ts
@@ -893,6 +893,7 @@
       element.patchRange = createPatchRange(1, 2);
       reportStub = sinon.stub(element.reporting, 'reportInteraction');
       await element.updateComplete;
+      reportStub.reset();
     });
 
     test('undefined', () => {