Powerchute agent outlet turning off - APC Smart UPS 1500

[Gre25692]

Our APC 1500 has recently been turning off its outlets randomly, maybe 3 times in past 2 months.

Its been getting alerts stating its compensating for overvoltage, AVR trim and boost going active then non-active just before the outlets turn off.

I'm in the UK so the power settings is below.

Rated Output Voltage 230V

Upper Limit 253V

Lower Limit 207V

Green Mode enabled

Sensitivity Low

Is there anything that could be wrong with the device?  Don't see any other alerts or any hardware errors.

The current input voltage seems to be sitting at about 250V which I know is quite high but its still within the 230V+10%, not sure if the input is going way beyond this when the outlets turn off as cant see any logs of what the voltage was at that moment in time.

Any help or ideas would be appreciated.