I have the same issue with my LG B8 55 (OLED55B8PLA).
After some time TV starts resetting input HDMI names. Not all at once, but step by step.
I'm using 3 inputs: ARC for the soundbar, Apple TV and TV box from internet provider (Vodafone).
Also USB flash drive is always in TV.
I can't figure out the logic behind resetting and I'm sure that this is a bug.
Did someone try to reset the TV to factory settings? Does it help?