Pivot chart colour formatting reverts back to inverse white

This is driving me insane. I have a clustered bar chart and I need to make the bars green for the negative values. But every time I close and reopen the spreadsheet the inverse colour reverts back to white. There are slicers in my spreadsheet but none connected to this particular pivot table & chart and it does not have any filters either.

I'm using Excel 2013, I've had to colour each bar manually for now but I need a permanent solution.

Any suggestions appreciated.

A little difficult to diagnose the issue without sight of the file.
Perhaps you could attach a sanitized version for us to see?

Click on GO ADVANCED and then scroll down to Manage Attachments to open the upload window.
Should be straightforward from there.

BSB

Screenshot.png

I've tried to attach a screenshot, axis and title removed but you get the idea - the white bars are supposed to be green.