I'm fairly sure you don't want that spacer between the frame and the bb cup, as the alba is a road crank. That would be why the cranks aren't spinning freely. Take that off then refit the bb without it.
I'm assuming that the plastic bearing covers that came with your gxp bb are slightly narrower than the spacers that come with praxis bbs which might cause the knocking
this
vs this
although the internet seems to suggest you can fit Sram cranks in the Praxis BB so not sure why you couldn't go the other way.
I'm fairly sure you don't want that spacer between the frame and the bb cup, as the alba is a road crank. That would be why the cranks aren't spinning freely. Take that off then refit the bb without it.
I'm assuming that the plastic bearing covers that came with your gxp bb are slightly narrower than the spacers that come with praxis bbs which might cause the knocking
this
vs this
although the internet seems to suggest you can fit Sram cranks in the Praxis BB so not sure why you couldn't go the other way.