Tvheadend

Hello,
I've been trialing a setup with a RPi3 B+ running on LibreELEC 9.2 (Kodi 18.5) and a USB DVB-T stick.
It's going ok. I feel this setup still has some rough edges to be worked on.
The thing that I find most annoying is that I can't zap (quickly change channels) by simply using the ^ / V (up/down) keys.

Everywhere I look on the internet it says that I can use the up/down arrow keys to change channels but I can't do that with my setup.
Mind you that I am not using a regular keyboard. I am using a TV remote using HDMI-CEC (LG's implementation called 'Simplink').
The up/down keys of the remote work just fine on Kodi's menus but when I'm watching Live TV with Kodi, pressing either up/down will simply display a OSD with the synopsis of the tv show I am currently watching.
Can someone tell me how I can workaround this issue?
Thanks in advance.
Cheers