Requirements:

zabbix version: 3.4.12

1. You need to configure at least one custom action

Steps to reproduce:

1. Wait until trigger was fired
2. Wait until zabbix run action for trigger event
3. Disable trigger
4. Reenable trigger

Result:
Action does not start after trigger reenabled

Sent counter does not increase
Expected:

Action will start for this trigger at next iteration

Sent counter will be increased