If you’re trying to change (or detect changes of) a client object, like a Gui, then the behavior might not be replicating to the client/server the way you expect. Try using a RemoteEvent to send a message to the server from a LocalScript, using the LocalScript to detect when something changes on the client object (the Gui.)
The transparency only changes for the client, so the Server wouldn’t see it. Like others mentioned, you would probably have to use RemoteEvents or somehow server-client communication