Ive mix matched adapter and charging cables from orher brands so that shouldn't be a issue, have you tried rebooting the device? If still happening then go into safe mode see still a issue then back out.
Welcome to Android Central! I believe it's normal on any phone for the charging icon to show (i.e. the lightning bolt in the battery icon in the status bar) when the phone is plugged in, even when the battery is 100%.