GROSS Withholding Tax lines automatically added to invoices but cannot work out why

Summary:

GROSS Withholding Tax lines automatically added to invoices but cannot work out why

Content (required):

When creating invoices - e.g. via IDR Invoice Scanning, an invoice header is created.

We can manually add an invoice line, but when going to Taxes -> Withholding Taxes, a zero value Tax line with a GROSS Rate is automatically added:

This happens for suppliers where Use Withholding Tax is not ticked:

And on Site, no WHT setup is enabled:

Settings under "Manage Tax Reporting and Withholding Tax Options" is as follows:

We do not want these zero value GROSS Tax lines to be added, because otherwise, when it comes to cancelling an invoice line we get this error: