Excel sparkline chart errors with consistent data values

[Andrew Brewster]

I have a worksheet with a group of sparkline charts, two rows of which use identical values in every cell in their data ranges, yet they show two types of errors

• A sudden step change in values
• A random change in values

All the other sparklines in the group have constantly varying data which is represented accurately.

It doesn't make a difference if I create them as a group or individually, in Office Online or the desktop client (2013)

Anyone got any idea of what's going on?

[#2]

@Andrew Brewster 

That could be rounding error if values are calculatable. In any case it's better to check sample file.