Change to how GST is treated - now overcharging

Something appears to have changed recently with how transactions treat the GST on items. Historically, the Customer Card drove how the GST was treated on a sale regardless of how the item was configured. 

Our inventory has items that are set up as EITHER ex- or inc- GST, and this is for particular purposes depending on, for instance, if it needs to be connected to website pricing. 

Now, when we enter a transaction to an overseas based customer who should be treated as a GST-Free, the transaction is saying it's GST-Free but the dollar value is actually inclusive of sales tax. In the below example, I'm demonstrating this error. For a customer located overseas, the item AVS-415 should be $249.86. The customer card is configured correctly per the above. 

Any explanation on why this has changed, or if it is a recent bug that can be remediated would be appreciated. We have an extensive catalogue, and it's now impossible to know in any instance if the system is reliably calculating sales tax, or if prices are suddenly becoming more expensive for customers, therefore making the transaction appear to be less competitive.