Disable the Automation feature. Most likely it is overriding your back to battery setting.
I don't care much for the Automation feature in SA. I tried setting it a few times, the result was operation I did not like. Adam made a video about SA on the EG4 6500EX long ago and he was as confused as anyone else.
If you have it set for back to grid in the 48V area, which I use and not 47V, it will switch to grid. When it hits back to battery voltage, which you want set at 53V, then it will switch back to battery.
I do have charging set for grid and solar, I see you have solar only.