Unsupported backend error for HDF5 file with `group` parameter

I haven't dug into the root cause of this error yet, but the following request results in an error which I would like to troubleshoot:

(GPM IMERG HH)
https://staging.openveda.cloud/api/titiler-cmr/tiles/WebMercatorQuad/0/0/0?scale=1&concept_id=C2723754847-GES_DISC&datetime=2018-02-12T09%3A00%3A00Z&group=Grid&variable=precipitation&backend=xarray

Error:

```
unrecognized engine zarr must be one of your download engines: ['h5netcdf', 'rasterio', 'store']
```

Noting this same error occurs for a similar request but for an NSIDC SMAP dataset:

https://staging.openveda.cloud/api/titiler-cmr/tiles/WebMercatorQuad/0/0/0?scale=1&concept_id=C3480440870-NSIDC_CPRD&datetime=2018-02-12T09%3A00%3A00Z&group=Geophysical_Data&variable=precipitation_total_surface_flux&backend=xarray