New issue 820: "all" particle type fields are dimensionless https://bitbucket.org/yt_analysis/yt/issue/820/all-particle-type-fields-are-...

Britton Smith:

All particles fields that are accessed with "all" are now being returned as dimensionless. For example, with an enzo-3.0 dataset:

data["all", "particle_mass"] returns dimensionless, but data["DarkMatter", "particle_mass"] returns the proper units.