Thanks! Unfortunately all the command does is remove the 1080p x 30Hz option in Kodi!
Checking the TV manual the HDMI connections are supposed to support 1080p at 24Hz, 50Hz & 60Hz.
The TV displays the resolution for about 1/2 second and the RPi2 running LibreElec 8.0 is definitely running at 1080p x 50Hz as set in Kodi.
I now have memories of using xrandr and cvt to define a resolution a year or two ago. All I can think is that before I discovered OpenElec I was using Kodi on Ubuntu and had this same problem on the two nettop clients. Unfortunately neither cvt or gtf seem to work on LibreElec to produce the modeline.
For comparison this is output when my old original Kodi Pentium4/Nvidia 210 Video client is connected to the same TV which runs at 1080p x 50Hz.
LibreELEC (official) Version: 7.0.2()
LibreELEC6:~ # xrandr
Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 8192 x 8192
DVI-I-0 disconnected primary (normal left inverted right x axis y axis)
VGA-0 disconnected (normal left inverted right x axis y axis)
DVI-I-1 disconnected (normal left inverted right x axis y axis)
HDMI-0 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 890mm x 500mm
1920x1080 60.05 + 59.94 50.00* 23.97 60.00 50.04
1440x480 60.05
1280x720 60.00 59.94 50.00
720x576 50.00 50.08
720x480 59.94 60.05
640x480 59.94 59.93
LibreELEC6:~ #
I have only just noticed that my satellite set top box connected to the other HDMI connection runs at 1080i but there is no option to change this in the box setup. The simple work around seems to be to resort to 1080i x 25 Hz as I cannot detect any problems with the picture and the TV detects it as 1080i x 50Hz.
Thanks for the help
Chris