I suddenly started having the same exact problem. Morry's suggestion above did not fix it. I believe it may have started because I had updated to the new OS 10.9.4 security update. I even tried closing the project and creating a new project with the new template, and the same problem still exists. Even when I go a song that I recorded previously, if I add an arrangement marker it only shows marker and the drummer will not populate with into, verse, chorus even if I change the marker name to intro, verse, chorus. Anyone else having the same problem?