SQL Server connector does not persist LSNs in Kafka

I have several connectors running for at least a month. A few of them seem not to store proper offsets in Kafka topic. Below are two sample entries in Kafka offset topic:

CreateTime:1546609528972    ["prod.XXXX",{"server":"prod.XXXX"}]    {"change_lsn":"0003d5c5:0000bcdd:00ca"}
CreateTime:1546609528974    ["prod.YYYY",{"server":"prod.YYYY"}]    {"snapshot":true,"snapshot_completed":true}

Both connectors are continuously processing events and continuously persisting to offset topic. The first one persists increasing lsns while the second one always persists the same information (

).