Trigger status stuck?

[lou.degenaro]

I'm a bit of a newbie. I'm running Zabbix 3.0.9. © 2001–2017, Zabbix SIA.

Initially my application (DUCC) is up.
Monitoring -> Web defined monitor that shows [myhost] DUCC"] status = OK.
I have a trigger expression: {myhost:web.test.error["[myhost] DUCC"].str(OK)}=0
Initially the Monitoring->Triggers display Status column = OK.

Then I purposefully shutdown my application (DUCC).
Monitoring -> Web shows [myhost] DUCC"] status = "Step 1 of 3 failed" and as expected Monitoring->Triggers display Status column = PROBLEM (and e-maul is sent too - yay!).

Then I re-start my application.
As expected, Monitoring -> Web shows [myhost] DUCC"] status = OK.
But there is never any change for the trigger: Monitoring->Triggers display Status column = PROBLEM. Why does is not revert to OK?

Furthermore, stopping and starting my application results in no further e-mails??

Please suggest what may be wrong here.

Thanks.

Lou.

[lou.degenaro]

I changed my expression to: {myhost:web.test.fail["[myhost] DUCC"].last()}>0 and get the switch between PROBLEM and OK.