Problem on running Powershell Script Alert

I have set only allow signed powershell script in my Local Group Policy and signed my Powershell script.

The signed script works fine when I manually ran it.

However, when I tried to trigger it with Alert Manger it failed and returned me an exit code.

Does anyone know how to solve this?

My execution policy is as follows:

Scope ExecutionPolicy
----- ---------------
MachinePolicy AllSigned
UserPolicy Undefined
Process Undefined
CurrentUser Undefined
LocalMachine Undefined