Bug when using Calculate with variables

Hey, everyone.

I'm having a problem with Calculate and Variables.

This is the data I generated for the Proof of Concept

I'm trying to obtain the sum of amount in each category, which is fairly easy using calculate such as:

Amount in Legal (no var) = 
CALCULATE(SUM('Planilha1 (2)'[Amount]);FILTER('Planilha1 (2)';'Planilha1 (2)'[Category] = "Legal"))

Result:

I can do this for each one and it would work.

The problem is when I try to use amount as a variable:

Amount in Legal = 
var amount = SUM('Planilha1 (2)'[Amount])
return
CALCULATE(amount;FILTER('Planilha1 (2)';'Planilha1 (2)'[Category] = "Legal"))

Result:

This is only a silly example, but it has affected me because I like to use lots of variables to keep the code organized and I have about 100 measures in each report.

If someone else has encountered this problem let me know. I'm also uploading this to Power BI Issues.

I can upload my pbix example for anyone who asks me.

Thanks,

Bruno Rodrigues.