Manual 'Allocate' button on 'Edit Taxes' on AP Invoice

Summary:

When a tax amount is entered manually on AP invoice, and user wanted to split the amount across all the lines (so that the tax split can copy the item expense lines distributions).

But when the tax amount is entered manually and 'Allocate' button on 'Edit taxes', the tax amount is not allocated as per the amounts / percentages entered on the lines, the tax amount is not allocated to all the lines as expected.

Please let us know if there is any pre-requisite for this Manual Tax Allocation to all the invoice lines.

Also is there any way to achieve this requirement please?