Not able to Modify Designed Slicers, Tables and Pivot Tables

[placebo96799]

I frequently make design changes in slicers, tables and pivot tables for aesthetic reasons. I have always been able to reopen the "Design" tab and reformat my designs. Recently, on one of my more complex spreadsheets, clicking on the Design tab does nothing. As a test I copied a data table from the affected spreadsheet to a new spreadsheet. I could modify the copied table. ............ Is my spreadsheet corrupt? Does anyone have a fix or any suggestions? Thanks