AutoMatching: Transaction Reference's calculated score is 100 when blank

Summary:

When we leave the remittance reference field blank, the automatching calculates the score as 100% which gives a 0.4 (out of 1) weighting to the recommendation. As our automatching rules are as follows:

Transaction Reference: 0.4

Customer: 0.3

Amount: 0.3

And our threshold is 0.6. When only the customer matches and the transaction reference wasn't provided, these invoices are still appearing as recommendations due to the blank remittance reference providing 0.4 weighting, plus customer 0.3 totaling 0.7.

Is there a way to make it so when the remittance reference is blank, then this returns a calculated score of 0?

Thanks!