Modbus Data reporting NaN with HA 2023.9.1

[Malcs91TF]

I have been successfully using this code until recently. Unfortunately with HA 2023.9.1 I find that all the Modbus values are being displayed as nan and being listed as Unavailable on the Entities page. This appears to be related to a change made in this latest HA version.

My guess is that we now need to reject invalid data to prevent the sensors being made unavailable if they are not detected when the Modbus link is first started. Does anyone have the same experience or knowledge on how to solve this ?