Which App(iOS/Android) are you using? I'd recommend creating a new test extension and testing with the 3CX Webclient to make sure it has nothing to do with the configuration of your current extension.While on a call, second call goes directly to VM. Allow multiple calls is enabled. Is there a way to have a call waiting notification?

Do let us know how it go.Now testing the in App forwarding options. I will follow up soon.
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