% compared to 1 row in Matrix

Mate,

First of all, please let these golden rules of data modeling sink in well:

Fact tables should never be exposed to the user. NEVER, EVER. All columns in them MUST be hidden unconditionally. Slicing is only ever done through dimensions.

Second of all, here's the measure:

% prod 2 = 
var __current = [Sum amount]
var __prod =
    CALCULATE(
        [Sum amount],
        categories[Group] = "production",
        all(categories)
    )
return
    DIVIDE(__current, __prod)

I think this is what you've been looking for...

For the future. Please try to learn as much as possible about good design and data modeling practices. It'll help you avoid pitfalls and production of numbers you will not be able to explain. Just a piece of good advice from a BI old-timer. You'll thank me later.

Best

D