Sorting by another column - unique id - please help

Create a new table with the category and subcategory, and add sort order columns. Follow along in this example and apply it to your situation.

For example, here are some various animals that fall into two categories (Mammal and Reptile), sorted with the Reptiles first then the mammals second, in the specific order that I want both the categories of Mammal and Reptile to be sorted, as well as the subcategories of Animal Name.  In this table, I sorted "Family" by "Family Sort Order" and "Animal Name" by "Animal Sort Order"

This will act as a dimension table.

Here is a fact table containing the count of each animal.

Add a many-to-one connection on the smallest subcategory in your hierarchy. In this case, Animal Name.

Now, your visual, you can use the "Animal Name" column from the dimension table with "Count" from your fact table,  then "sort by" Animal Name Ascending in the visual, and it will be in the correct order.  Snake, Lizard, Cat, Zebra, Dog, Elephant.  Note that this is not sorted alphabetically, not sorted by ascending Y axis value etc.  It is sorting using the order I dictated in my dimension table. 

Here is the data  in a matrix, with the Category and Subcategory both sorted correctly.

 See attached .pbix file.

EDIT:

If you have problems because your Subcategory values are not unique to each Category like they are in my animals example, follow these directions.  For example if you have "Revenue" subcategory within both "Net Profit" category as well as "Profit" categories.

Add a "Key" column to both tables. (I did [Family] & "-" & [Animal Name]) to uniquely idenfify each combination of Family and Animal Name.

Add a Key sort order column with the order you want them sorted, taking into account both the categories and subcategories.

Then use that Key column to create the relationship.

etc etc...

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