Miracast MICE may be blocked while a VPN connection is running on the connecting device (laptop).
First test if the Miracast connection is working as expected with the VPN disabled or not connected. If it is working, the VPN will block local access when active. Be aware that this setting may be different depending on the used VPN platform.
As an example, the setting used in Cisco Secure Client is shown. Make sure that the option Allow local (LAN) access when using VPN (if configured) is enabled (by default, disabled).