Subcontract retention Release - Tax amount incorrect for negative lines

     I am encountering this issue when I am trying to release retention of a negative quantity line

For Example the quantity is -2 and unit price is 2600

so the line value is -5200

I created claim for -5200 and 5 percent retention which makes it as

Debit RNV                                      = -5200

Debit Gst Payable                          = -494

Credit Accounts Payable                = 5434

Credit AP Retention                        = 260

Debit Gst Payable                           = -26

Credit Gst Deferred                         = 26

When I am clearing retention

Debit AP Retention                = -260

Credit Gst Payable                = 26

Debit Gst Payable                 = -26

Debit Gst Deferred                = -26

Credit Accounts Payable       = 286

but the tax calculation comes out as below

you can see that the tax amount is calculated with a positive sign. Has anyone come across it?