Toggle to show or hide warnings like query errors and no results messages in the rendered report. Show Warnings is enabled by default; to hide warnings, disable it from the Design ribbon.
When warnings are enabled, an error message will appear inside any visual that couldn't be rendered in the exported report. For instance, if you have interactions between visuals or slicers from different data models, and haven't configured cross model mapping, the affected visuals will not be rendered. If warnings are enabled, an error message will be shown (as seen in the image below); if warnings are disabled, the visual will simply appear blank.