GST / Service Tax on Area Given under Joint Development Agreement - Goods and Services Tax - GST

Respected Seniors and Experts, I have one querry as below : One of my client is a Builder/Developer. He entered into a JDA with landowner for Development of Land in the month of February 2016. Terms of Agreement were Area Sharing. We discharged Service Tax liability on Area to be handed over to Landowner under Construction Services in the quarter 4 of 2015-2016. This tax liability was discharged following POT Rules on the basis of Consideration received in advance in the form of Development Rights. We have entered into supplementary Agreement in the month of Sept 2019 for demarcation of units to be allotted to land owner. We received Occupancy Certificate in the month of September 2020. Now GST Department insist that We are liable to discharge GST on the units allotted to landowner following notification no. 4/2018. We replied that as per Sec. 142(11)(b) of GST Act, the supply on which Service tax was leviable on that service GST will not be levied. Now department has issued SCN on the same point. Can you please guide me with case laws Thanking you in Advance.