If the battery sat for a while, it's possible that it somehow got low enough from sitting (?) that it kicks in the BMS low voltage cut off (?)
Yout battery charger may be trying to charge/balance....make sense? If letting the battery sit on charger for 12 hours...then you check with
a digital volt meter and the battery still shows not being chared/charging ..then if it were me..i'd look into another charger.
If not the charger then it's something in your battery or the BMS.
Hope that helps.
Welcome to the forums by the way!!