diff --git a/src/main/java/uk/ac/cam/cl/dtg/segue/etl/ContentIndexer.java b/src/main/java/uk/ac/cam/cl/dtg/segue/etl/ContentIndexer.java
index a06d3ce8c3..acd2116f3f 100644
--- a/src/main/java/uk/ac/cam/cl/dtg/segue/etl/ContentIndexer.java
+++ b/src/main/java/uk/ac/cam/cl/dtg/segue/etl/ContentIndexer.java
@@ -61,6 +61,7 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
+import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -251,7 +252,7 @@ private synchronized void buildGitContentIndex(final String sha,
 
                         // add children (and parent) from flattened Set to
                         // cache if they have ids
-                        for (Content flattenedContent : this.flattenContentObjects(content)) {
+                        for (Content flattenedContent : flattenContentObjects(content)) {
                             if (flattenedContent.getId() == null) {
                                 continue;
                             }
@@ -386,6 +387,12 @@ private Content augmentChildContent(final Content content, final String canonica
             log.debug("Found question without id '{}' in {}", content.getTitle(), canonicalSourceFile);
         }
 
+        // Give title-less questions unique titles so they remain distinct in Set-based flattening, even if they have
+        // the same id.
+        if (content instanceof Question && content.getTitle() == null) {
+            content.setTitle("untitled-question-" + UUID.randomUUID());
+        }
+
         // Try to figure out the parent ids.
         String newParentId;
         if (null == parentId && content.getId() != null) {
@@ -1073,8 +1080,13 @@ && flattenContentObjects(content).stream()
             }
             // Verify that significant figure bounds are correct
             if (!q.getDisregardSignificantFigures()) {
-                if (null == q.getSignificantFiguresMin() ^ null == q.getSignificantFiguresMax()) {
-                    // Both bounds need to be present, or both not present
+                // If not 'exact answers only', s.f. bounds should be set
+                if (null == q.getSignificantFiguresMin() && null == q.getSignificantFiguresMax()) {
+                    this.registerContentProblem(content, "Numeric Question: " + q.getId() + " has no "
+                            + "significant figure bounds set. If this question does not use significant figures then "
+                            + "'exact answers only' should be set.", indexProblemCache);
+                } else if (null == q.getSignificantFiguresMin() || null == q.getSignificantFiguresMax()) {
+                    // Both bounds need to be present
                     this.registerContentProblem(content, "Numeric Question: " + q.getId() + " has only one "
                             + "significant figure bound, and may be unanswerable as a result. Please add both upper "
                             + "and lower significant figure bounds, or omit both.", indexProblemCache);
diff --git a/src/test/java/uk/ac/cam/cl/dtg/segue/etl/ContentIndexerTest.java b/src/test/java/uk/ac/cam/cl/dtg/segue/etl/ContentIndexerTest.java
index 8f53b11002..b359f26bf5 100644
--- a/src/test/java/uk/ac/cam/cl/dtg/segue/etl/ContentIndexerTest.java
+++ b/src/test/java/uk/ac/cam/cl/dtg/segue/etl/ContentIndexerTest.java
@@ -204,7 +204,7 @@ public void flattenContentObjects_flattenMultiTierObject_checkCorrectObjectRetur
     }
 
     /**
-     * Test that recordContentTypeSpecificError does not add an error message to indexProblemCache when neither
+     * Test that recordContentTypeSpecificError adds an error message to indexProblemCache when neither
      * significant figure is set whilst disregardSignificantFigures is not set.
      */
     @Test
@@ -221,7 +221,9 @@ public void recordContentTypeSpecificError_noSigFigSet_checkNoError() {
 
         // ASSERT
         for (Content key : indexProblemCache.keySet()) {
-            assertTrue(indexProblemCache.get(key).isEmpty());
+            for (String problem : indexProblemCache.get(key)) {
+                assertTrue(problem.contains("has no significant figure bounds set."));
+            }
         }
     }