12.7 volts with no charging is a full battery. It can't be any higher than that unless it's just some surface charge that hasn't bled off yet. Your charging seems to be working.
Has the power been disconnected from the Tri-Metric lately? If so, it loses track and needs to figure out where your batteries are again. It can only do this when they reach the fully charged parameters. Make sure your Tri-Metric's setting for fully charged isn't above the programmed voltage of your charging source. If it is, it will never decided that the batteries are full.