Want to bet that Wanda is a prisoner in the RAFT and, feeling guilty about her past activities (Westview, Multiverse), she isn't attempting to escape ? (although she could easily escape due to her abilities). Her appearance in the post-credits scene of "Avengers - Doomsday" would show where she had been all this time and prepare for her appearance in "Avengers - Secret Wars". (I like this theory I developedy I hope you do too.)