Steps to reproduce:

• Create a dummy Zabbix Trapper item
• Create a dummy trigger to trigger on last value > 5
• Create a dummy Action to perform anything like echo 123 > /tmp/dummy.log with an option to execute on Zabbix Server
• Fire up the trigger

Result:
Unnecessary colon is being placed before the command. please check the image attached
Expected:
Either Zabbix Server either the command without a colon.