FSG - Unable to use Offset with Amount Type "BAL-Actual (FY Start)"

We have 2 columns in our balance sheet FSG report:

1. Current YTD balance

2. YTD balance as on 31-Dec  (Static)

Since our financial year end is 30th Jun, December would always be Balance at start of year - 6 Offset

For this we have defined the column as follows:

Amount Type = BAL-Actual (FY Start)

Offset = -6

However the offset column shows null value