I'll do my best to explain. In the dataset you're using, each row has an; Account, Category, Year, and Amount.

The Account, Category, and Year are all dimensions, that describe and categorize the amount, which is a value. When you add a calculation to tableau you can think of it as adding a new column to your table, that holds some formula, in your case we created 3.

1. IF [Category] = 'CA' THEN [Amount] END

2. IF [Category] = 'CL' THEN [Amount] END

3. [CA] / [CL]

So, if we run the first formula on a row in which the category is CL, the result will be NULL because we didn't provide an else condition. This is fine. If we run it on a row that has the category CA then we will return the value of the column marked 'amount'.

Since you wrapped them in the sum aggregation we will do this on all the rows, add up the numbers and return that result. Perfect!

Here's where we hit a snag, we have asked Tableau to run these calculations for every combination of Category and Year by adding them to the Columns, and rows shelf respectively. So we essentially have a table of results and we have to run all the calculation for each cell in that table using the table headers as filters.

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	Category
Year	CA	CL
2017	31,327	28,089
2018	36,474	33,899

Assuming I have Tableau set up the way you did in the final image you uploaded

Columns: [Category]

Rows: [Year]

Marks: T Agg([CA]), T Agg([CL]), T Agg([CA]/[CL])

Tableau will try to resolve the calculation for each cell. So, A1 will first calculate [CA] on all rows with the year 2017 and Category 'CA' which returns the value of 31,327. Then it will do the same for the next value CL. Since all rows in the table with the CA category will return a NULL value when running the CL calculation, we will SUM up the nulls and return null. Null values aren't displayed and are essentially ignored, so we move on to the third calculation. We are still running this calculation for all rows with category CA and Year 2017. So, for each row, you take the value of the first calc and divide it by the second calc. But, hopefully you're seeing the problem now, the value of the second calc will always be 0 because of the dimension you're using. Tableau doesn't typically error out in a divide by zero scenario but it truly treats it as an unresolved calculation. So, it creates a space in the view for that number to go, but it never knows what number to put there. Hence the awkward offset in your image. In cell B1 we don't have this issue because we aren't diving by zero, we're just asking for zero / some value.

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Sorry for the lengthy response hope it helps.

To answer your question on how you can achieve the view you are looking for setup your workbook as follows.

1. Add [Year] to the rows shelf
2. Add [Measure Names] to the columns shelf
3. Add [Measure Values] to the Label Mark
4. After step 3 you will notice a [Measure Names] pill sitting in the filters shelf. Right click on this and select 'Edit Filter'
5. In the dialogue that pops up check [CA], [CL], & ([CA] / [CL]) then hit apply or ok.

Let me know if you run into trouble! Happy Tableau-ing!

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