Even the Tax Code is set to IM0, Tax field shows empty when processing K1 entry.
From K1 entry control, Tax field shows empty even the GST Tax Code set is IM0. To reflect the desired value of Tax Field which is "N/A", re-select the Tax Code and pick the "IM0" again. Upon doing this, "Total Value of Standard Rated Acquisition" from GST-03 will also be correct.
***Usually encountered when using lower versions (701 and below) and once upgraded to higher (e.g. 704, 706) or latest (708) versions.