I want to show the button, if the logged in user is part of an assignment group using UI action

[sreebeeraka]

I want to show the button, if the logged in user is part of an assignment group using UI action.

I tried to use this code -- gs.getUser().isMemberOf(current.assignment_group). 

Can anyone help me on this why it is not working in UI action. 

UI action checked fields:

1. Show Update - checked

2. Client - Checked

3. Form Button - Checked.

Condition: 

current.u_rfc_type=="Standard" && current.u_request_cancellation=="true"&&current.assignment_group.type.getDisplayValue()=="Abc Fulfiller"&&gs.getUser().isMemberOf(current.assignment_group)

It is working up to this condition:

current.u_rfc_type=="Standard" && current.u_request_cancellation=="true"&&current.assignment_group.type.getDisplayValue()=="Abc Fulfiller"

Not working if add the below condition for the above code:

&&gs.getUser().isMemberOf(current.assignment_group)

Is anyone face the same issue?

[sreebeeraka]

Yes i impersonated as group member and tried, the button is visible after page loading it is getting disappeared.

[Mark Stanger]

If the button appears for a split second on the form and then goes away the UI action condition is fine.  It's got to be a client script of some sort hiding it.