diff --git a/sync/catchup/boost.go b/sync/catchup/boost.go
index 264b0b4..c32fdcf 100644
--- a/sync/catchup/boost.go
+++ b/sync/catchup/boost.go
@@ -223,7 +223,7 @@ func (c *coordinator) dispatchLoop(ctx context.Context, wg *sync.WaitGroup) {
 						// Collect epoch data
 						c.collectEpochData(r.epochData)
 						r.epochData = nil // free memory
-					} else if r.isInvalidFilterError() && r.task.From < r.task.To {
+					} else if r.isInvalidFilterError() {
 						resultHistory = append(resultHistory, r)
 						// Invalid filter: try splitting and reassigning
 						c.recallTaskQueue <- r.task
@@ -307,12 +307,14 @@ func (c *coordinator) assignTasks(taskSize uint64) {
 			recallTask := <-c.recallTaskQueue
 			midEpoch := (recallTask.From + recallTask.To) / 2
 			c.pendingTaskQueue <- newSyncTask(recallTask.From, midEpoch)
-			c.pendingTaskQueue <- newSyncTask(midEpoch+1, recallTask.To)
+			if midEpoch+1 <= recallTask.To {
+				c.pendingTaskQueue <- newSyncTask(midEpoch+1, recallTask.To)
+			}
 			continue
 		}
 
 		// The full epoch range has been assigned
-		if c.nextAssignEpoch <= c.fullEpochRange.To {
+		if c.nextAssignEpoch > c.fullEpochRange.To {
 			break
 		}
 
@@ -437,18 +439,16 @@ func (s *boostSyncer) memoryMonitorLoop(ctx context.Context, c *coordinator) {
 
 // fetchAndPersistResults retrieves completed epoch data and persists them into the database.
 func (s *boostSyncer) fetchAndPersistResults(ctx context.Context, start, end uint64, bmarker *benchmarker) error {
-	var epochData *store.EpochData
-	var state persistState
-
 	timer := time.NewTimer(forcePersistenceInterval)
 	defer timer.Stop()
 
+	var state persistState
 	for eno := start; eno <= end; {
 		startTime := time.Now()
 		select {
 		case <-ctx.Done():
 			return ctx.Err()
-		case epochData = <-s.resultChan:
+		case epochData := <-s.resultChan:
 			// collect epoch data
 			if epochData.Number != eno {
 				return errors.Errorf("unexpected epoch collected, expected %v got %v", eno, epochData.Number)
@@ -458,28 +458,31 @@ func (s *boostSyncer) fetchAndPersistResults(ctx context.Context, start, end uin
 			}
 			eno++
 			s.monitor.Update(eno)
-		}
 
-		epochDbRows, storeDbRows := state.update(epochData)
-		if logrus.IsLevelEnabled(logrus.DebugLevel) {
-			logrus.WithFields(logrus.Fields{
-				"epochNo":            epochData.Number,
-				"epochDbRows":        epochDbRows,
-				"storeDbRows":        storeDbRows,
-				"state.insertDbRows": state.insertDbRows,
-				"state.totalDbRows":  state.totalDbRows,
-			}).Debug("Catch-up syncer collected new epoch data")
+			epochDbRows, storeDbRows := state.update(epochData)
+			if logrus.IsLevelEnabled(logrus.DebugLevel) {
+				logrus.WithFields(logrus.Fields{
+					"epochNo":            epochData.Number,
+					"epochDbRows":        epochDbRows,
+					"storeDbRows":        storeDbRows,
+					"state.insertDbRows": state.insertDbRows,
+					"state.totalDbRows":  state.totalDbRows,
+				}).Debug("Catch-up syncer collected new epoch data")
+			}
+		case <-timer.C:
+			// Force persist if timer expires
 		}
 
 		// Check if we need to persist now (due to timer expiration)
-		var forcePersist bool
+		forcePersist := false
 		select {
 		case <-timer.C:
 			forcePersist = true
 		default:
 		}
 
-		// Batch insert into db if enough db rows collected, also use total db rows here to restrict memory usage.
+		// Batch insert into db if `forcePersist` is true or enough db rows collected, also use total db rows here to
+		// check if we need to persist to restrict memory usage.
 		if forcePersist || state.totalDbRows >= s.maxDbRows || state.insertDbRows >= s.minBatchDbRows {
 			if err := s.persist(ctx, &state, bmarker); err != nil {
 				return err