Version

4.6.0

Reproduction link

https://jsfiddle.net/ue2h5z79/

Steps to reproduce

In the "options"->"visualMap" object change the "minOpen" proberty to "true".

What is expected?

I expect a piece to be added to the pieces in the chart, meaning that it should have 6 pieces now. 5 for the range between min and max value and 1 for values lower min.

What is actually happening?

The piece for lower than the min value is added, BUT suddenly the range between min and max value has one piece less and the last piece includes a bigger range than the others. It is still 5 pieces but I would expect 6.

If you change the "maxOpen" proberty to "true" it shows the expected behaviour, meaning it has now 6 pieces.