Hmm... those are the only things i could think of, unless she is in the basement... (I forgot her there once...) u may have to restart, or maybe devs can offer some help. Tho if it's a bug, they may need some extra details to find and fix it
did you complete the desert quest? I mean, did you visit the gold mine with Cassie? There is an option where Cassie stays with Michael in the slavers' hideout and you can go back to other locations without her. But after completing the gold mine, she always comes back.
