Is under investigation -
This Zabbix 4.0 is using an API script for manual closing as a remote command action (event.acknowledge)
And task manager process caused a deadlock in the update of the escalations table.

421712:20200502:063010.495 [Z3005] query failed: [1213] Deadlock found when trying to get lock; try restarting transaction [update escalations set r_eventid=13596195,nextcheck=0 where escalationid=4811173;update escalations set r_eventid=13596195,nextcheck=0 where escalationid=4811174;]

WebUI: Problem state does not change from "Closing" and manual close problem checkbox is disabled.
DB: r_event was not generated in events table. (eventid = 13596195)