SYSLOG stops being populated to SQL DB

Hi

Running rsyslog through Observium, works initially (as in syslogs appear in SQL DB) but somewhere along the way (~few hours maybe) the DB stops being populated with the syslog entries. Syslog entries still appear in the standard "messages" log file, i have turned on debugging and can see the entry logged in the observium debug.log but still doesn't appear in SQL DB,
Restarting rsyslog resolves this for a few hours until it stops again.
Any pointers on what to check?

running 0.15.7.6597
thanks