diff --git a/core/filtermaps/filtermaps.go b/core/filtermaps/filtermaps.go
index 18b1c7dc79..d40b48ea0c 100644
--- a/core/filtermaps/filtermaps.go
+++ b/core/filtermaps/filtermaps.go
@@ -144,7 +144,10 @@ type filterMap []FilterRow
 // copies made for snapshots during rendering.
 func (fm filterMap) copy() filterMap {
 	c := make(filterMap, len(fm))
-	copy(c, fm)
+	for i, row := range fm {
+		c[i] = make(FilterRow, len(row))
+		copy(c[i], row)
+	}
 	return c
 }
 
diff --git a/core/filtermaps/map_renderer.go b/core/filtermaps/map_renderer.go
index 28f943abb3..4341d4707b 100644
--- a/core/filtermaps/map_renderer.go
+++ b/core/filtermaps/map_renderer.go
@@ -84,7 +84,7 @@ func (f *FilterMaps) renderMapsBefore(renderBefore uint32) (*mapRenderer, error)
 	if err != nil {
 		return nil, err
 	}
-	if snapshot := f.lastCanonicalSnapshotBefore(renderBefore); snapshot != nil && snapshot.mapIndex >= nextMap {
+	if snapshot := f.lastCanonicalSnapshotOfMap(nextMap); snapshot != nil {
 		return f.renderMapsFromSnapshot(snapshot)
 	}
 	if nextMap >= renderBefore {
@@ -97,7 +97,7 @@ func (f *FilterMaps) renderMapsBefore(renderBefore uint32) (*mapRenderer, error)
 // snapshot made at a block boundary.
 func (f *FilterMaps) renderMapsFromSnapshot(cp *renderedMap) (*mapRenderer, error) {
 	f.testSnapshotUsed = true
-	iter, err := f.newLogIteratorFromBlockDelimiter(cp.lastBlock)
+	iter, err := f.newLogIteratorFromBlockDelimiter(cp.lastBlock, cp.headDelimiter)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create log iterator from block delimiter %d: %v", cp.lastBlock, err)
 	}
@@ -137,14 +137,14 @@ func (f *FilterMaps) renderMapsFromMapBoundary(firstMap, renderBefore uint32, st
 	}, nil
 }
 
-// lastCanonicalSnapshotBefore returns the latest cached snapshot that matches
-// the current targetView.
-func (f *FilterMaps) lastCanonicalSnapshotBefore(renderBefore uint32) *renderedMap {
+// lastCanonicalSnapshotOfMap returns the latest cached snapshot of the given map
+// that is also consistent with the current targetView.
+func (f *FilterMaps) lastCanonicalSnapshotOfMap(mapIndex uint32) *renderedMap {
 	var best *renderedMap
 	for _, blockNumber := range f.renderSnapshots.Keys() {
 		if cp, _ := f.renderSnapshots.Get(blockNumber); cp != nil && blockNumber < f.indexedRange.blocks.AfterLast() &&
 			blockNumber <= f.targetView.headNumber && f.targetView.getBlockId(blockNumber) == cp.lastBlockId &&
-			cp.mapIndex < renderBefore && (best == nil || blockNumber > best.lastBlock) {
+			cp.mapIndex == mapIndex && (best == nil || blockNumber > best.lastBlock) {
 			best = cp
 		}
 	}
@@ -171,10 +171,9 @@ func (f *FilterMaps) lastCanonicalMapBoundaryBefore(renderBefore uint32) (nextMa
 		if err != nil {
 			return 0, 0, 0, fmt.Errorf("failed to retrieve last block of reverse iterated map %d: %v", mapIndex, err)
 		}
-		if lastBlock >= f.indexedView.headNumber || lastBlock >= f.targetView.headNumber ||
-			lastBlockId != f.targetView.getBlockId(lastBlock) {
-			// map is not full or inconsistent with targetView; roll back
-			continue
+		if (f.indexedRange.headIndexed && mapIndex >= f.indexedRange.maps.Last()) ||
+			lastBlock > f.targetView.headNumber || lastBlockId != f.targetView.getBlockId(lastBlock) {
+			continue // map is not full or inconsistent with targetView; roll back
 		}
 		lvPtr, err := f.getBlockLvPointer(lastBlock)
 		if err != nil {
@@ -257,10 +256,13 @@ func (f *FilterMaps) loadHeadSnapshot() error {
 
 // makeSnapshot creates a snapshot of the current state of the rendered map.
 func (r *mapRenderer) makeSnapshot() {
-	r.f.renderSnapshots.Add(r.iterator.blockNumber, &renderedMap{
+	if r.iterator.blockNumber != r.currentMap.lastBlock {
+		panic("iterator state inconsistent with last block")
+	}
+	r.f.renderSnapshots.Add(r.currentMap.lastBlock, &renderedMap{
 		filterMap:     r.currentMap.filterMap.copy(),
 		mapIndex:      r.currentMap.mapIndex,
-		lastBlock:     r.iterator.blockNumber,
+		lastBlock:     r.currentMap.lastBlock,
 		lastBlockId:   r.f.targetView.getBlockId(r.currentMap.lastBlock),
 		blockLvPtrs:   r.currentMap.blockLvPtrs,
 		finished:      true,
@@ -661,24 +663,13 @@ var errUnindexedRange = errors.New("unindexed range")
 // newLogIteratorFromBlockDelimiter creates a logIterator starting at the
 // given block's first log value entry (the block delimiter), according to the
 // current targetView.
-func (f *FilterMaps) newLogIteratorFromBlockDelimiter(blockNumber uint64) (*logIterator, error) {
+func (f *FilterMaps) newLogIteratorFromBlockDelimiter(blockNumber, lvIndex uint64) (*logIterator, error) {
 	if blockNumber > f.targetView.headNumber {
-		return nil, fmt.Errorf("iterator entry point %d after target chain head block %d", blockNumber, f.targetView.headNumber)
+		return nil, fmt.Errorf("iterator entry point %d after target chain head block %d", blockNumber, f.targetView.ProcessedHead())
 	}
 	if !f.indexedRange.blocks.Includes(blockNumber) {
 		return nil, errUnindexedRange
 	}
-	var lvIndex uint64
-	if f.indexedRange.headIndexed && blockNumber+1 == f.indexedRange.blocks.AfterLast() {
-		lvIndex = f.indexedRange.headDelimiter
-	} else {
-		var err error
-		lvIndex, err = f.getBlockLvPointer(blockNumber + 1)
-		if err != nil {
-			return nil, fmt.Errorf("failed to retrieve log value pointer of block %d after delimiter: %v", blockNumber+1, err)
-		}
-		lvIndex--
-	}
 	finished := blockNumber == f.targetView.headNumber
 	l := &logIterator{
 		chainView:   f.targetView,