Hello,
Whilst on holidays, I have followed a similar bug report on an LG 40UB800V television via ticket.
In that case, the EDID was different in each mode of the television.
Resolution of 4Kp60 was not in the EDID of the PC mode, only on the HDMI-DTV mode.
The limited colour space in that mode was also not supported.
Your description fits the conclusion and description from LG website.
https://www.lg.com/uk/support/produc...8590776-others
Kind regards,
Alban