Bug: Burnup chart is displaying information incorrectly and "back tracking"

Summary

The customer is utilizing iterations in their milestones and noticed a visual error in their burn up chart (image attached). They reported it to me today, but they said at least one user has seen this same error previously but they did not report it. Customer is self managed running on version 15.11.2-ee

Steps to reproduce

If this bug is reproduced, it should be done using a self-managed instance running 15.11.2. Then, view burndown/burnup charts associated with an open milestone utilizing iteration cadences.

Example Project

N/A

What is the current bug behavior?

The burn up chart is "back tracking" and not moving forward. The line goes from July 23, to July 24, then reverses and goes back to July 23 instead of moving to July 25. Image is attached

What is the expected correct behavior?

The line should not move backward.

Relevant logs and/or screenshots