CFA Virtualisation using CMIP6 example data: Unable to aggregate

Example CMIP6 data (JASMIN)

files = [
    '/badc/cmip6/data/CMIP6/ScenarioMIP/CNRM-CERFACS/CNRM-ESM2-1/ssp119/r1i1p1f2/3hr/huss/gr/v20190328/huss_3hr_CNRM-ESM2-1_ssp119_r1i1p1f2_gr_201501010300-203501010000.nc',
    '/badc/cmip6/data/CMIP6/ScenarioMIP/CNRM-CERFACS/CNRM-ESM2-1/ssp119/r1i1p1f2/3hr/huss/gr/v20190328/huss_3hr_CNRM-ESM2-1_ssp119_r1i1p1f2_gr_203501010300-205501010000.nc',
    '/badc/cmip6/data/CMIP6/ScenarioMIP/CNRM-CERFACS/CNRM-ESM2-1/ssp119/r1i1p1f2/3hr/huss/gr/v20190328/huss_3hr_CNRM-ESM2-1_ssp119_r1i1p1f2_gr_205501010300-207501010000.nc',
    '/badc/cmip6/data/CMIP6/ScenarioMIP/CNRM-CERFACS/CNRM-ESM2-1/ssp119/r1i1p1f2/3hr/huss/gr/v20190328/huss_3hr_CNRM-ESM2-1_ssp119_r1i1p1f2_gr_207501010300-209501010000.nc',
    '/badc/cmip6/data/CMIP6/ScenarioMIP/CNRM-CERFACS/CNRM-ESM2-1/ssp119/r1i1p1f2/3hr/huss/gr/v20190328/huss_3hr_CNRM-ESM2-1_ssp119_r1i1p1f2_gr_209501010300-210101010000.nc'
]

Attempted to aggregate the first two example files (successful)

f = cf.read(files)
g = cf.aggregate(f[:2])

Normal cf.write functions properly here by creating a combined netCDF file of both files, but using with cfa=True results in one of the following, depending on if I take the whole of both Fields (116880 time steps):

RuntimeError: NetCDF: HDF error

or a subselection of the last 10 from file 1 and the first 10 from file 2 .

g = cf.aggregate([ f[0][-10:], f[1][:10] ])

File "/home/users/dwest77/Documents/cfa_python_dw/cf_dw/cf_python/cf/read_write/netcdf/netcdfwrite.py", line 106, in _write_as_cfa
    raise ValueError(
ValueError: Can't write <CF Field: specific_humidity(time(20), latitude(128), longitude(256)) 1> as a CFA-netCDF aggregation variable. Consider setting cfa={'strict': False}

cf-python 3.16.2 (latest)
cfdm 1.11.1.0 (latest)

Start by reproducing the two examples with cf.read, cf.aggregate, and cf.write(cfa=True), then inspect cf/read_write/netcdf/netcdfwrite.py at _write_as_cfa. Compare the full and boundary-subset cases, and use the reported HDF error and strict-mode ValueError to trace the failing CFA-netCDF path. Done means the examples can be written with cfa=True without those failures.