I seem to fall over that problems again and again: When I import footage, which I worked on in AE - e.g. created a Mask inside footage and exported it from AE with Animation Codec including the Alpha Channel - I do not seem to be able to make FCP understand and see that part to make it transparent.
Same thing for PS - when I worked on some titles - exporting it with transparent background - FCP makes it opaque and does not recognize its transparecy. Even when I set the layer's composite mode to Alpha Channel.
Yes, the AE is also in my MAC. I managed to fix it with setting the Alpha Channel in the Browser Tab.
I still struggle though sometimes with Still coming from PhotoShop - it doesn't wanna recognize the A-Channel there. Specially, when I create something that is supposed to work as an A-Channel Mask.