Numbers 6.2.1 - Cant' Alphabetize

Use to be able to sort a whole table (rows, columns, multiple cells) alphabetically on a spreadsheet in the previous version of Numbers on our old Mac.

Since upgrading our Mac we are using Numbers 6.2.1. We open documents that were migrated over to the new computer. Now in this latest version of Numbers we're unable to alphabetize a spreadsheet as table. Instead, each column with alphabetize independenty, leading to rows that are mismatched with data.

We tried a lot of things. We checked the preferences settings. We followed the suggestions listed in the Help search. Since the Sort Now button is greyed out. We checked for any merged cells and found none.

We need further direction. Thank you. Barb