KEPServerEX (OPC UA Client) unable to update the Security Policy to "None"

1) Top diagram is work properly before. Due to client's decision and to avoid the data lost because of client/server certificate need to renew every 3 years. we are agreed to change the security policy to "None"
2) I have completed change the security level to "None" on the UA sever side. I have perform the loop back test and it's successfully (re-create the channel to connect locally).
3) When I want to change the security policy from "Basic256Sha256" to "None". the setting on the UA client keep fall back to "Basic256Sha256" once I click the Apply and OK button.

4) I tried to disable the tag scanning and configure, the result still the same.

would it be the Authentication issue? default OPCUser issue? the log of the configuration HMI is showing i'm the administrator. seem like I can't update the security setting on UA client.