5 files changed, 27 insertions, 8 deletions
diff --git a/source/blender/editors/transform/transform_convert_sequencer.c b/source/blender/editors/transform/transform_convert_sequencer.c
index 17512c79d03..45ed0f3b664 100644
--- a/source/blender/editors/transform/transform_convert_sequencer.c
+++ b/source/blender/editors/transform/transform_convert_sequencer.c
@@ -400,15 +400,14 @@ static void seq_transform_handle_overlap(TransInfo *t, SeqCollection *transforme
   if (seq_transform_check_strip_effects(transformed_strips)) {
     /* Update effect strips based on strips just moved in time. */
     seq_transform_update_effects(t, transformed_strips);
+  }
 
-    /* If any effects still overlap, we need to move them up. */
-    Sequence *seq;
-    SEQ_ITERATOR_FOREACH (seq, transformed_strips) {
-      if ((seq->type & SEQ_TYPE_EFFECT) && seq->seq1) {
-        if (SEQ_transform_test_overlap(seqbasep, seq)) {
-          SEQ_transform_seqbase_shuffle(seqbasep, seq, t->scene);
-        }
-      }
+  /* If any effects still overlap, we need to move them up.
+   * In some cases other strips can be overlapping still, see T90646. */
+  Sequence *seq;
+  SEQ_ITERATOR_FOREACH (seq, transformed_strips) {
+    if (SEQ_transform_test_overlap(seqbasep, seq)) {
+      SEQ_transform_seqbase_shuffle(seqbasep, seq, t->scene);
     }
   }
 }
diff --git a/source/blender/sequencer/CMakeLists.txt b/source/blender/sequencer/CMakeLists.txt
index e324bc8b407..f060e6ad69b 100644
--- a/source/blender/sequencer/CMakeLists.txt
+++ b/source/blender/sequencer/CMakeLists.txt
@@ -33,6 +33,7 @@ set(INC
   ../render
   ../windowmanager
   ../../../intern/atomic
+  ../../../intern/clog
   ../../../intern/guardedalloc
 
   # dna_type_offsets.h
diff --git a/source/blender/sequencer/SEQ_iterator.h b/source/blender/sequencer/SEQ_iterator.h
index cb2091511a9..3ade7309f89 100644
--- a/source/blender/sequencer/SEQ_iterator.h
+++ b/source/blender/sequencer/SEQ_iterator.h
@@ -73,6 +73,7 @@ struct Sequence *SEQ_iterator_yield(SeqIterator *iterator);
 SeqCollection *SEQ_collection_create(const char *name);
 SeqCollection *SEQ_collection_duplicate(SeqCollection *collection);
 uint SEQ_collection_len(const SeqCollection *collection);
+bool SEQ_collection_has_strip(const struct Sequence *seq, const SeqCollection *collection);
 bool SEQ_collection_append_strip(struct Sequence *seq, SeqCollection *data);
 bool SEQ_collection_remove_strip(struct Sequence *seq, SeqCollection *data);
 void SEQ_collection_free(SeqCollection *collection);
diff --git a/source/blender/sequencer/intern/iterator.c b/source/blender/sequencer/intern/iterator.c
index 09f033e70fb..333a8e46c44 100644
--- a/source/blender/sequencer/intern/iterator.c
+++ b/source/blender/sequencer/intern/iterator.c
@@ -123,6 +123,14 @@ uint SEQ_collection_len(const SeqCollection *collection)
 }
 
 /**
+ * Check if seq is in collection.
+ */
+bool SEQ_collection_has_strip(const Sequence *seq, const SeqCollection *collection)
+{
+  return BLI_gset_haskey(collection->set, seq);
+}
+
+/**
  * Query strips from seqbase. seq_reference is used by query function as filter condition.
  *
  * \param seq_reference: reference strip for query function
diff --git a/source/blender/sequencer/intern/strip_transform.c b/source/blender/sequencer/intern/strip_transform.c
index c9af2fced65..9f69f434ca0 100644
--- a/source/blender/sequencer/intern/strip_transform.c
+++ b/source/blender/sequencer/intern/strip_transform.c
@@ -40,6 +40,10 @@
 #include "SEQ_time.h"
 #include "SEQ_transform.h"
 
+#include "CLG_log.h"
+
+static CLG_LogRef LOG = {"seq.strip_transform"};
+
 static int seq_tx_get_start(Sequence *seq)
 {
   return seq->start;
@@ -315,6 +319,12 @@ static int shuffle_seq_time_offset_test(SeqCollection *strips_to_shuffle,
       if (!seq_overlap(seq, seq_other)) {
         continue;
       }
+      if (UNLIKELY(SEQ_collection_has_strip(seq_other, strips_to_shuffle))) {
+        CLOG_WARN(&LOG,
+                  "Strip overlaps with itself or another strip, that is to be shuffled."
+                  "This should never happen.");
+        continue;
+      }
       if (dir == 'L') {
         offset = min_ii(offset, seq_other->startdisp - seq->enddisp);
       }