Business Process Required Floating Point field needs to be > 0.0 ?

I have a floating point field (defined as an optional field in the schema) placed in a Business Process Flow stage and marked as a 'required field' in the BPF. When no value specified, the field reads 'click to enter' and if I try to move to the next stage, this (rightly fails). However, it still fails if the value entered is zero (0.0). Any number > 0.0 will allow the process to move on. Zero is a valid value and used to work prior to our upgade to Dynamics 365.

Is this a bug? Does anyone know how to work around this.

Many thanks.