I do not think many use the SterlingPower chargers as they are fairly expensive for what they are even compared to Victron and sure compared to Renogy models.
Not sure what happens but since battery never gets to 14.4V the charger should never be in any other charge stage except for the first one the bulk (constant current). Not sure what the reason is for the charger to be in any other charge stage.
The way a Lead Acid charger should work (and this one is no different as LiFePO4 setting on all this chargers is a gimmick) it to have those multiple stages minimum 3 of them bulk (constant current), absorption (constant voltage 14.4V) and then when current on absorption charging drops to around 10% of max current it should enter in float (also constant voltage but lower voltage).
So since a 4s LiFePO4 controlled by the SBMS0 with default settings the voltage will never get to 14.4V the charger should be always in bulk mode charging at max current 30A in your case and as soon as any cell gets to 3.55V meaning full battery the charging should just stop then when battery discharges charging should start again in bulk mode and again it will not be able to get to 14.4V so can not get to absorption mode.
Since you mentioned you use short and super thick cables it is not possible for the charger to see a higher voltage than battery not by enough to think it got to 14.4V and ven if that was to be the case it should be in absorption charging so it should still push as much current very close to 30A until current drops to around 3A (10%) before going in to next stage with reduced voltage and that could never happen. Unless the charger is fairly off and his internal measurement is much lower than real battery voltage so say battery is 13.7V but the charger reads it as 14.4V then it will think is already in absorption mode (constant voltage) so it will not allow battery to charge and reduc current maintaining what he thinks is 14.4V but in reality it is just 13.7V thus current will fairly soon fall to below 3A and then enter next stage conditioning or float.