[Eddie Mor]

Hello from Spain,

as far as I Know, Apple pro res 12 bit 4444 is not equal to 10 bit 444 ( without the alpha channel ) , with the alpha channel is 16 bit 4444
So, the problem is that FCP cannot edit or export in 12 BIT, Only 10 or 8, so you loose colour depth from your source, to conforme you need another machine using edl or xml,

I would hope someone tell me I´m wrong ( really )

https://support.apple.com/kb/HT5151