Edit: We have uncovered three '18 MBPs all with the same bug highlighted below. As I think is the case with USB-C MBPs, my '18 15" has a power chime that plays when the power is connected or the battery becomes full. This is irritating when I work and someone may be napping, and it's just plain not necessary. It appears that /System/Library/CoreServices/PowerChime.app/Contents/Resources/connect_power.aif is played in this case. I am unable (even as sudo in terminal) to delete or change this file. I just don't understand why there isn't an option to turn this feature off when the machine is muted. Does anyone know a way around this? Thanks!