pt-table-checksum stuck on "Waiting to check replicas for differences"

Polyglot Projects Percona Toolkit
1

When I run pt-table-checksum, it keep printing,

Waiting to check replicas for differences: 0% 00:00 remain

Waiting to check replicas for differences: 0% 00:00 remain

Waiting to check replicas for differences: 0% 00:00 remain

Waiting to check replicas for differences: 0% 00:00 remain

Waiting to check replicas for differences: 0% 00:00 remain

and I checked the log on slave, it also loop,
171129 8:34:10 88 Query SELECT MAX(chunk) FROM percona.checksums WHERE db=‘test’ AND tbl=‘_logs’ AND master_crc IS NOT NULL

171129 8:34:11 88 Query SELECT MAX(chunk) FROM percona.checksums WHERE db=‘test’ AND tbl=‘_logs’ AND master_crc IS NOT NULL

171129 8:34:12 88 Query SELECT MAX(chunk) FROM percona.checksums WHERE db=‘test’ AND tbl=‘_logs’ AND master_crc IS NOT NULL

171129 8:34:13 88 Query SELECT MAX(chunk) FROM percona.checksums WHERE db=‘test’ AND tbl=‘_logs’ AND master_crc IS NOT NULL

171129 8:34:15 88 Query SELECT MAX(chunk) FROM percona.checksums WHERE db=‘test’ AND tbl=‘_logs’ AND master_crc IS NOT NULL

171129 8:34:16 88 Query SELECT MAX(chunk) FROM percona.checksums WHERE db=‘test’ AND tbl=‘_logs’ AND master_crc IS NOT NULL

…