diff --git a/src/npc_sync/sync.py b/src/npc_sync/sync.py
index 45c1c92..6a7de5e 100644
--- a/src/npc_sync/sync.py
+++ b/src/npc_sync/sync.py
@@ -196,7 +196,8 @@ class SyncDataset:
 
 
     """
-
+    blocks_using_diode: tuple[bool, ...]
+    
     def __init__(self, path) -> None:
         if isinstance(path, self.__class__):
             self = path
@@ -1131,6 +1132,7 @@ def is_mismatch(edges, block) -> bool:
                     )
 
         frame_display_time_blocks: list[npt.NDArray[np.floating]] = []
+        blocks_using_diode = [True] * len(vsync_times_in_blocks)
         for block_idx, (vsyncs, rising, falling) in enumerate(
             zip(
                 vsync_times_in_blocks,
@@ -1185,6 +1187,7 @@ def short_interval_indices(diode_flips):
                     frame_display_time_blocks.append(
                         self.constant_lag_frame_display_time_blocks[block_idx]
                     )
+                    blocks_using_diode[block_idx] = False
                     continue
 
                 def score(diode_flips, vsyncs) -> float:
@@ -1236,6 +1239,7 @@ def median_diff(diode_flips, vsyncs) -> float:
                         frame_display_time_blocks.append(
                             self.constant_lag_frame_display_time_blocks[block_idx]
                         )
+                        blocks_using_diode[block_idx] = False
                         aborted = True
                         break
                     logger.debug("Missing first diode flip")
@@ -1294,6 +1298,7 @@ def median_diff(diode_flips, vsyncs) -> float:
                         frame_display_time_blocks.append(
                             self.constant_lag_frame_display_time_blocks[block_idx]
                         )
+                        blocks_using_diode[block_idx] = False
                         continue
                     logger.exception(error_text)
                     import matplotlib.pyplot as plt
@@ -1356,7 +1361,8 @@ def median_diff(diode_flips, vsyncs) -> float:
             frametimes = diode_flips + MONITOR_CENTER_REFRESH_TIME
             frame_display_time_blocks.append(frametimes)
 
-        assert len(frame_display_time_blocks) == len(self.vsync_times_in_blocks)
+        assert len(frame_display_time_blocks) == len(self.vsync_times_in_blocks) == len(blocks_using_diode)
+        self.blocks_using_diode = tuple(blocks_using_diode)
         return tuple(frame_display_time_blocks)
 
     @property