Applied Tax on PO is disappeared after doing change in shipment line
We made a PO of one item/line with 5 shipment lines (on the basis of Need by Date) & applied GST-2%. After receiving partial qty against shipment line 1; as per business need we cancelled remaining shipment lines (2, 3, & 4) & added a new line (#5 with different Org & Location) of remaining quantities (sum of quantities of line 2,3, & 4 plus partial remaining quantity of line 1).
The tax applied against line #1 is disappeared & even Mange Tax option is not allowing to apply it again (i.e. tax addition is disabled against line #1). However system is allowing to add tax on newly added line (#5).
Please guide how to rectify the said issue & how to save the occurrence of the same in future.