IF and CASE statements are processed from top to bottom. So when you select multiple quarters the IF condition is returning True and therefore returns the Actuals. I can't be exactly sure of the reason why because you're using a ATTR() as an aggregation and haven't shared a screenshot of your view or a Tableau packaged workbook for me to look at so I'm not sure how your view is set up that would cause that to be the case. If you still need help on this I suggest posting a Tableau packaged workbook with some sample data and your work so far, please see Packaged workbooks and flows: when, why, how for more info.
Hi Jonathan -- You are correct, ATTR was preventing the table from working correctly. Thanks for the reply!