Harmony Remote & HDMI-CEC

Hi - sorry for another forum about Harmony remotes & HDMI-CEC but I am just in the process of setting up my new Harmony remote to work with Rasplex and I am almost there. I have one small strange problem - whenever activate the ‘Watch Plex’ actively the sequence is as follows;

-Power on AV Receiver (Sony STR-DH820)
-Power on TV (Samsung)
-Switch Samsung TV to HDMI (This is the ARC HDMI)
-Switch AV Receiver to SAT (i.e. the input for Rasplex)

The strange problem is after it starts up the TV/HDMI-CEC seems to do a few more buttons presses (specifically ‘OK’ button and then back twice). Any ideas why this would be happening - I am guessing some CEC small error but I cannot figure out what if any delays would help this.

Thanks!