Have just tried a different USB port on the Pi3 - diagonally opposite - saw another post about some potential USB hub conflicts. This *seems* to have fixed it for now, am about to setup another (have another 2) so will see how I go.
Using Mac v3.1.0 - firmware v4.2.2 - in Advanced, there is no inter-key delay? Has it been removed? Am getting key repeats with a Sky HD+ remote (usually the left/right buttons), various post say inter-key delay is the 'key' to resolve but it doesn't seem to exist anymore/in the Mac version? Have tried wiping the configuration, reloading, remapping, still seems to be left/right directions. Also tried 2 different Sky HD+ remotes.