Strange issue affecting FES2014 correlations

[robbibt]

Have encountered a strange issue with missing rectangular areas in output correlations based on FES2014 data:

As far as I can tell, this seems to only affect FES2014, despite outputs from all models looking theoretically identical and not containing any obvious differences in value ranges, dtypes or nodata. Best theory is that it's something to do with xr.corr (although other correlation funcs encounter the same problem), or some coordinate dtype issue with multiindexes?

Can reproduce by running the following geometry with `tide_model = "FES2014":

from odc.geo.geom import Geometry, CRS
study_area = "bugfix"
geom = Geometry({'type': 'Polygon', 'coordinates': (((1879630.0, -3690430.0), (1879630.0, -3699980.0), (1888280.0, -3699980.0), (1888280.0, -3690430.0), (1879630.0, -3690430.0)),)}, CRS('PROJCS["GDA94 / Australian Albers",GEOGCS["GDA94",DATUM["Geocentric_Datum_of_Australia_1994",SPHEROID["GRS 1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],AUTHORITY["EPSG","6283"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4283"]],PROJECTION["Albers_Conic_Equal_Area"],PARAMETER["latitude_of_center",0],PARAMETER["longitude_of_center",132],PARAMETER["standard_parallel_1",-18],PARAMETER["standard_parallel_2",-36],PARAMETER["false_easting",0],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","3577"]]'))