Interval as dimension shows up twice in chart

[wayne-a]

Hi I'm having an issue with an interval that is being used as a dimension.  The dimension is defined as a master item dimension as follows:  =interval([Delivered Date] - [In Transit Date], 'mm')

Works fine when I use it in a table but I want a chart that can show the number of things, in this case orders, based on the interval.  For example how many orders had an interval of 1 minute between these dates.  I'm using a line chart that has the interval as a dimension on the x axis and the counts on the y axis.  On the x axis I'm seeing the interval twice as in the example below.  

The data seems simple, here is a straight table with the information.

The only thing I can think of is that the interval returns a dual so is the interval function returning two "types" but the interval value is the same?

We are on the November 2018 patch 1 release if that is important.  Thanks in advance for any help or insight.

[sunny_talwar · Accepted solution]

Interval alone is a formatting function... so although you display just mm, there might be seconds or date information attached to it... try this may be

=Interval#(Interval([Delivered Date] - [In Transit Date], 'mm'), 'mm')

[wayne-a]

Hi Sunny, as always, you are spot on.  Thanks for the explanation and solution.  Solved!