Fix grid item progressive propagation logic

Set the top level grid item's progressive to be true only if all
the grid items have progressive set to true (and not just the
first one).

src/read.c

@@ -1426,6 +1426,7 @@ static avifResult avifDecoderGenerateImageGridTiles(avifDecoder * decoder, avifI
     // Count number of dimg for this item, bail out if it doesn't match perfectly
     unsigned int tilesAvailable = 0;
     avifDecoderItem * firstTileItem = NULL;
+    avifBool progressive = AVIF_TRUE;
     for (uint32_t i = 0; i < gridItem->meta->items.count; ++i) {
         avifDecoderItem * item = gridItem->meta->items.item[i];
         if (item->dimgForID != gridItem->id) {
@@ -1490,9 +1491,6 @@ static avifResult avifDecoderGenerateImageGridTiles(avifDecoder * decoder, avifI
             AVIF_CHECKERR(dstProp != NULL, AVIF_RESULT_OUT_OF_MEMORY);
             *dstProp = *srcProp;
 
-            if (itemCategory == AVIF_ITEM_COLOR && item->progressive) {
-                gridItem->progressive = AVIF_TRUE; // Propagate the progressive status to the top-level grid item.
-            }
         } else if (memcmp(item->type, firstTileItem->type, 4)) {
             // MIAF (ISO 23000-22:2019), Section 7.3.11.4.1:
             //   All input images of a grid image item shall use the same coding format [...]
@@ -1504,8 +1502,15 @@ static avifResult avifDecoderGenerateImageGridTiles(avifDecoder * decoder, avifI
                                   (const char *)firstTileItem->type);
             return AVIF_RESULT_INVALID_IMAGE_GRID;
         }
+        if (!item->progressive) {
+            progressive = AVIF_FALSE;
+        }
         ++tilesAvailable;
     }
+    if (itemCategory == AVIF_ITEM_COLOR && progressive) {
+        // If all the items that make up the grid are progressive, then propagate that status to the top-level grid item.
+        gridItem->progressive = AVIF_TRUE;
+    }
 
     if (tilesAvailable != grid->rows * grid->columns) {
         avifDiagnosticsPrintf(&decoder->diag,