Just as a heads up, this issue is probably the same as this issue that has been fixed and added to the 8.0.1 patch on Dec. 12th 2019:
Charting, reporting, and visualization issues
Date resolved: 2019-11-08
Issue number: SPL-179171, SPL-178113
Description: Editing color scale using colorpalette in dashboard creates custom configuration
I can't 100% confirm this fixes the issue, til I get a chance to try it out in a couple weeks.
But since it took me a while to find, I figured I'd add it to this page to hopefully help others.
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