anchor: 'free' breaks fixed range with multiple axes

[matinh]

This issue is already described in detail in the plotly forum. Here is just a short summary:

On a scatter plot with multiple (three) axes/traces each axis should have a range with a dynamic (autorange) lower bound like this:

var layout = {
    // ...
    yaxis: {
        range: [null,200],
        autorange: 'min'
    },
    // ...

For 3 traces/axes, this is not working as expected! A complete SSCCE is available on codepen. The example works fine for two traces, but once a third trace is enabled (uncomment line 10), the autorange stops working.

This issue seems only to exist of anchor is set to free for the axes. However, when using multiple axes, the anchor has to be free for meaningful axes-positioning.