Intercompany invoice check box on invoice header

Summary:

We have noticed that the Intercompany Invoice checkbox on the Invoice header is automatically enabled by the system based on the Supplier selection. However, it appears enabled for some suppliers but not for others, even when the supplier type is set to Intercompany. Additionally, if an intercompany supplier is entered incorrectly, the checkbox remains enabled. If we remove the supplier name and then enter an external supplier, the checkbox still stays enabled.

Could you please explain the logic behind this behaviour and advise how to deselect the checkbox when the wrong supplier is chosen?

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