There’s a bug in the importer, search on the forum. Hopefully there will be a commit to fix this soon.
This may be it: FIX: The order of includes in the base importer was wrong. · gschlager/discourse@827daf7 · GitHub
Edit 1 : I just created a new setup with v1.2.0.beta5, now importing Vanilla 2 export
Edit 2: It worked