Why some Purchase invoices are found under Posted Purchase Invoice and some are found under Posted Purchase Tax Invoice

Hi NAV Guru,

My client have posted purchase invoices and some appear under Posted Purchase Invoice page and some appear under Posted Purchase Tax Invoice page.

Notice it is not happening as per vendor, there is scenario where same vendor will have invoices sitting at Posted Purchase Invoice page and Posted Purchase Tax Invoice page.

May i know why is that the case?

Regards,

Susy