Logitech K380 function keys not working with Karabiner.

[Clive]

Running latest version of Big Sur on iMac. I want my K380 functions keys to work as standard function keys not as media control.  If I select "Use all F1,F2 etc. keys as standard function keys" in the Logi App I have to quit Karibiner to get it to work. I've tried various rules but nothing seems to work. Any help would be really appreciated!