My inverter is X1-Hybrid-LV, when I set return to utility soc to 10%, but when the soc comes to 10%, but didnt be charged,why?

Our LV inverter logic is like that when the inverter connects the lithium battery,then if the return to utility soc sets at 15%,then when soc comes to 15%,it will only be charged when the soc belows 15,which means 15 is not the value which can trigger the charged process, only it comes to14%,then it will be charged, and sometimes may have some delay, but it is normal, just wait for a while, but it will be charged before the soc comes to 13%

Note: all the lithium battery has these logic, not only our ld53 battery