Conditional formatting tables
Conditional formatting in tables, at the moment, attempting to apply conditional formatting to a table causes the document to become incredibly unstable especially as the database size grows. It's also incredibly unwieldy.
Conditional formatting in general should probably be updated to be more dynamic and consistent with other aspects of Excel, it doesn't appear that conditional formatting has changed much since much earlier versions of Excel.
PivotTables also automatically break conditional formatting of entire rows or columns of data. It would be nice to be able to apply conditional formatting dynamically to rows of data in PivotTables.