Identical daily BMS-related warnings and retractions

We are having an unusual phenomenon on a customer Victron Quattro 48V 10kW system. In the space of 1 minute there are 4 fault reports followed by 4 fault cancellations, as follows :-

#67 No BMS on Solar Charger [258]
#67 No BMS on Solar Charger [256]
#67 No BMS on Solar Charger [288]
Low Battery on VMS Bus System [0]
BMS lost on VMS Bus System [0]
#67 No BMS cleared on Solar Charger [258]
#67 No BMS cleared on Solar Charger [256]
#67 No BMS cleared on Solar Charger [288]
Low Battery cleared on VMS Bus System [0]
BMS lost cleared on VMS Bus System [0]

The behaviour of the system does not seem to be adversely affected.
The sequence happens regularly every day, seemingly when

  1. The battery SOC falls to the low threshold
  2. The battery SOC rises to 100%.

The batteries are 3 x Freedom Won eTower units ?

Has anyone seen this before ? Any suggestions as to what the solution might be ?