Surprising it even started with a voltage over 13. Most 'smart' chargers would see that and just go right to float voltage.
I would have to unplug my schumacher, load battery until it read ~12.6v, and then only then restart it to get it to seek 14.x at whatever amp rate I chose.
Did you ever test amperage readout against another ammeter?
My schumacher never displayed amps. Now it does not display anything, but it still works. I have a wattmeter on its output to see what it is doing and have to remember what buttons to press to get tit to AGM and 2 12 or 25 amps. It is on the screwy 31 which rarely gets cycled now, but top charged often.