Difficult to answer without seeing the structure of your data and the structure of your text table, but let's say you have something like this that you want to sort by date:

The easiest way to do this would be to drag another Order Date pill onto the rows shelf in the very first position, then set it to sort:

You can then right-click on that pill and de-select "Show Header" which will hide the value:

Your table will now look the like original, but will be sorted by date.

I think this workaround is still required in. 2018.3