External Monitor inactive

[Phil 1]

I have Recalbox set up with a Raspberry Pi4 inside a RasPad 3 which is a portable tablet. It works great but so far I have been unable to use the second hdmi port to use with an external monitor.
On boot up the external monitor will show the usual Recalbox intro but remains static when the boot is finished and only the tablet screen operates.
Does anyone know how to activate the second hdmi so I can use the tablet with an external monitor?
Any suggestions would be greatly appreciated thanks.

[Gaemish]

I had the exact same issue (Recalbox/Pi4/Raspad3), ended up removing the Pi4 from the Raspad3, hooked it directly to the TV using the mini(?)-Hdmi0 and everything worked perfectly. So I'm thinking the issue is the Raspad3s use of the two mini-Hdmi ports combined to form the regular Hdmi port.