Inspiron 23-5348, unlock keyboard in HDMI input mode

Hi,

I have my PS4 connected to my Dell Inspiron 5348 through the HDMI input and also my TV through the HDMI output.

When I put my Dell onto show second screen only using project (Win+P) then press the switch screen/ HDMI input button at the side to show the PS4 I can see my desktop on the TV but no input is registered on the mouse and keyboard (except Ctrl Alt Del). Is there anyway I can unlock the mouse and keyboard so that I can have functionality of the PC while in the monitor mode?

PS - I know it’s possible as it has randomly occurred before.