This seems to be an issue with the scale, so when there is only one data the default behavior is considering it as a date but after transforming it's considered as a number and the junk value is coming as last 3 digits of the number i.e, in your case startTime: "1574504520049" is .049

So if you update the scale to somewhere near that you will be able to get time as

d3.zoomIdentity.translate(100, 50).scale(0.0000000001)

enter image description here

Please check

it will help you find a proper scale for the problem.

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