Battery charge indicators mismatch

I have a 2013 48V MID EV. It has just under 50 hours. For the last year - it takes several attempts to get the battery discharge indicator with the red bars to show fully charged, even though the charge status indicator shows charged (steady green). I will unplug and re-plug and try again. Almost always it takes two attempts, occasionally three attempts. Another strange thing is that the subsequent attempts are faster that the original attempt, almost as if the batteries are really charged.

Any thoughts on what could be wrong or how to trouble shoot the problem?

Is there a way to tell if the battery is actually fully charged, even though the battery discharge indicator shows just a couple of red bars?