Video does not start on pc when controlling via smartphone

I have a computer working as a media server. It runs ubuntu and it is connected via HDMI to a dumb TV. When the computer is powered on, it runs a command line script to open Plex. I then use a smartphone to control Plex and start playing the videos.

However, the video only starts playing when I click on the pc, despite the tv showing a black frame with the play/pause symbol. Currently to solve the problem, I added to the launching script an order to click somewhere on the screen, but this is a very ducktape solution given that I need to wait for the webpage to fully load and find a place with no links to click on.

Do you know of an alternative solution? The ideal situation is to power on the computer an start playing Plex videos with no interaction.