xarray.open_dataset gained the ability to open HDF5 files in 0.12.0. However, this can cause Python to quietly crash without error message, which can be quite confusing. This is true even with the minimum required versions of xarray, h5py and h5netcdf installed.
We don't have a specific workaround for this other than to use h5py directly. We have used h5py for several years in high-stakes operations, including data analysis and data collection. Both h5py and netcdf4 Python modules work with context managers to avoid excess I/O resource consumption.