Freedomwon and Sunsynk voltage

Hi all, hope this is in the right place.

I have 2 freedomwon 5kw etowers and a Sunsynk 5kw inverter. I recently added the 2nd battery to a battery that was 3 years old, which had been rock solid since installation. Here's the issue, I see that at times the battery voltage on the inverter shows 56.1v which is higher than the max of 56. I noticed after adding the 2nd battery and went back on the history and it had been happening since I had system set up. I have contacted freedomwon and checked the settings, 55.5v for float, abaorbtion and equalization, all correct, some people said lower it which I did but it keeps going to 56.1 when fully charged. I have contacted sunsynk for a firmware upgrade, and waiting since that was freedomwons suggestion. Any ideas on how to resolve this as it all works perfectly, no errors but don't know if it's just an error with the inverters reporting but don't want to damage the batteries. Any ideas to reduce the voltage at max charge?

I thought of just letting the batteries charge to 99% but imagine they won't balance then.

Thanks