Synchronize clips

I'm trying to synchronize clips in Premiere Pro from a concert I shot.  I’m using footage from two cameras and an external audio source and I would like to synchronize them.  When I try to use a multicam sequence, audio isn’t showing up as a synchronization option. Whenever I tried to just synchronize the clips, the synchronize button is grayed out. I have been troubleshooting for hours with no progress. My application is updated, all clips have audio, and I converted the external audio to wav. I feel as though I've tried everything and there is nothing changing. Help would be appreciated!