Lately Logic Pro X has not been automatically converting the sample rates of our recorded tracks. We podcast with 4 hosts and for some reason 3/4 of us are recording at 48K. The project is set to 44.1K and in the past Logic Pro X would match the sample rates when importing. Not so much any more. It’s super buggy under El Capitan as well (Good job Apple!)
So you can force Logic Pro to down sample the tracks. In the Audio Bin, control click the tracks and chose Copy/Convert. Then choose AIF and set the sample rate to 44.1K. Also leave the Change File reference in Project Audio. Logic Pro X will freeze up (way to go Apple!) but after a while you will see a project bar as the track converts to the final file.