Logbook is empty

Configuration
1

Hello everyone. I’ve got issue with Logbook. There is no new records for last two days. Earlier records are present. I have following warning in log:
17-02-05 21:06:26 WARNING (Thread-9) [homeassistant.components.recorder] Ended unfinished session (id=76 from 2017-02-05 17:42:11)
How can I solve the issue?

Thank you in advacne

2

It’s strange but history is present.

3

Finally I’ve found the reason why Logbook was not updating. The reason was Russian characters in two my sensors - WU and Google calendar.
So this is preventing logbook from adding new entities.