I have this nifty data story on my coffee spend that I use for such tests. When I changed the Report's "Export Data" setting from "Summarized Data" (the default) to "None", it also did the following:
Turned all Visual Borders off
Turned all Visual Backgrounds off
Turned all Visual Titles off
Broke my Bookmarks/Buttons (they just stop responding)
Removed my Custom Color Theme (though curiously the legend still shows the old color)
I know the change to Export caused it because I didn't change anything else, the "surprise" change is reflected in the Workspace while the "correct" formatting still shows in the App.
I restored the original formatting by republishing my PBIX file, but when I tried the Export Control again I saw the exact same unintended formatting change. My Power BI Desktop is version September 2018.
See the "Before" & "After" images below. I'm assuming this is a bug?
If I understand your scenario correctly that the "Before" image is the Report setting for Summarized Data and the"After" image is the Report setting for None?
If it is, I cannot reproduce your issue in my Power BI Service.
If it is convenient, could you share a dummy pbix file which can reproduce the scenario, so that I can have a test in my site? You can upload it to OneDrive or Dropbox and post the link here. Do mask sensitive data before uploading.)
Community Support Team _ Cherry Gao If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.