ALV Block List Subtotal

I have an ALV Block List and in the block list there are multiple currencies and amounts. When i use the subtotal button the expected output is to display calculated total amounts for each of the currencies.

Whats actually happening is that the total is returning an X.

Please note that i have used the field catalog field of cfieldname for the amount.

I also noticed that this only happens when using ALV Block List but when the same thing is done in ALV List totals are being calculated by currency as expected.