The PCB in my Amprobe AMP-25 is virtually identical.
Mine always reads 120-140mA in AC mode, with no way to zero it out, although LPF mode is better at around 50mA. But it is still accurate at values just above that. So if I give it 250mA AC, it is pretty much spot on.
DC accuracy seems similar to what you've observed.
Major gripes are no min/max/average, no peak/inrush in DC mode, no zero/relative in AC mode.
I've attached the calibration procedure for the AMP-25 in case anyone needs it, perhaps it is the same for all of them.