Did you get this resolved? Did OP?
I've been going thru the same thing with my new 4S pack - at full charge voltages, anything over about 3.45V per cell I had a run-away cell or two that would trip the over-volt on the BMS. I did a $-ton of searching, even found this thread.
I fixed it by bleeding current off the high cells with a resistive load - a automotive light bulb - that would take the top cells down to match the others. Most of the time the upper one was in balancing mode on the BMS, the extra load just made it work faster. And with a limited current as the cells reach peak charge, lowering the top one pushes the lower ones up. Fun to watch on the BMS app, especially when the delta reaches zero!
Now I can get full 3.6V charge on all my cells without tripping BMS over-volt.
Another way is to apply a top charge to the lower cell terminals to bring them up to match the rest of the pack.
If your bank doesn't maintain it's balance then there's likely a variance in resistance or capacity between the cells within your pack/bank.
I've been adjusting charge settings for ideal performance exactly they way sandals has been saying. If your cells can be balanced and stay balanced, you can utilize the higher charge voltage and resultant current, and full capacity of your bank.
I just hope they stay balanced over many cycles!