I have two of these connected in parallel to my two SNA5000WPV inverters in battery shared mode. It seems that after each load shedding episode the batteries do not charge fully. Yesterday evening the batteries stopped discharging at around 36%, battery voltage low. When it started charging however it started at 0%. It seems a complete discharge resets the BMS and the full capacity of the battery is available for a few load shedding cycles.

What voltages do you charge them to? And how long have you had them. I suspect it's related to an unbalanced cell and the way they configured the BMS. The best solution is probably to send it back.