Measure summary shows 3.64e-12 for Inverted amount column

Hi All 

I am trying to understand this below issue where invertned measure total of Base Amount(-) is coming with wrong values and wrongly summarises with coming exponential values. However it should be coming with 0 as per showing in Base Amount column. You can see from first image that Total is comming but metrix visulisation is showing 3.64E-12 instead of 0 for Third quarter value.  

Below is measure forumula is used but not sure why this is not working correclty. Any idea here?

Measure

Base Amount:=sum([Base Amount (£)])

Base Amount (-):=Sum([Base Amount Inverted])

Calculated Column

Base Amount Inverted:=[Base Amount (£)] *1

Regards

Vrajesh