Are you running a particular version of a beta tag? If so, can you let me know which beta tag you are on so that I can have a look?
In the compatibility file we have < 3.2.0.beta2: 1398eeeff550c1da186a47b6d3878d3230f62340 which states the any Discourse version smaller than 3.2.0.beta2 will pin the theme to the 1398eeeff550c1da186a47b6d3878d3230f62340 commit hash.