Hello @Stuart,
Thank You for posting your query onto the Forum.
Well by looking at the scenario right now, the problem is not with the formula but it’s with the naming convention that being defined into the format. Since the same naming convention has been followed for all the “Detailed P&L” particulars it’s causing the problems and providing you the errorneous/ambiguous results.
I’m providing you a link of the post where this same sort of problem was highlighted by one our forum member and how it got resolved.
The only solution to resolve this type of problem is to create a unique naming convention. Please go through the link provided below which will guide you how to solve this problem.
Hoping you find this useful and solves your problem. 
Important Note: Please click onto the link to view the entire post and not onto the expand/collapse button.
Thanks and Warm Regards,
Harsh