We uses Zabbix 1.8.15. On Monitoring --> IT servises --> SLA found hardnode hn9 with downtime but status is OK and it really works (hn9_sla_today.png).
Also there were no problem triggers on Dashboard (Monitoring).
Open Monitoring --> Events -->Host <hn9> and found that according trigger 00:09:28 "Server hn9 is unreachable" has status OK previously than status PROBLEM and its durations are equal 1m 02s (hn9_sla_events.png).
At 09:33 manually executed trigger actuating to PROBLEM and after to OK (hn9_sla_events_restart.png) last trigger status seted to OK.
After that SLA started calculating as hardnode hn9 is up and duration of old trigger PROBLEM at 00:10:30 turned to 9h 22m (period to 09:33:13).

What the reason that Event values are incorrect?
Can it affects SLA?

Such problems found on another Zabbix servers (1.8.15).
How we can fix it?