I am experiencing an interesting problem which is that I have a plain vanilla install of Librelec 9.1 on an RPi4. While my TV supports 2160p60 and my FireTV stick is able to use that resolution the RPI runs only on 2160p30. I cannot change it in Settings/System to anything more than 30Hz. Anyone have a recommendation on how to diagnose/change that so that the Raspi displays at 60Hz.