Sort by error, duplicate values where there appear to be none

Please follow the steps below to have it work. Adjust it accordingly. 

Step 1

 Create a Custom Table with all the category either manually in Power Query or Summarize Table.

Create a new column beside and provide the number in the order you want to arrange.

Step 2

Create a relationship between the column in actual table to the custom sort table

Step 3

Create a column in Actual table with an expression.

Sort order = RELATED(CustomSortTable[Sort])

Step 4

Select the column you want to sort, and a “Column Tools” menu bar will appear at the top. Now Select the “Sort by column” and select the sort order column.