AMML stress property not found for calculator vasp

Including the stress property in a Property parameter returns the following error:

File "/hkfs/home/project/hk-project-consulting/an9294/python_VirtEnvs/vrel-mstr/lib/python3.9/site-packages/virtmat/language/utilities/amml.py", line 544, in get_ase_property
    raise PropertyError(msg)  # not covered
virtmat.language.utilities.errors.PropertyError: no property "stress" found for calculator "vasp"

The setup of the vasp calculator is as follows:

calc =  Calculator vasp == 6.4.3 (
            (algo: 'Fast'),
            (ediff: 1e-06) [electron_volt],
            (ediffg: -0.005) [electron_volt / angstrom],
            (ibrion: 2),
            (isif: 2),
            (ismear: 1),
            (ispin: 2),
            (lcharg: false),
            (lwave: false),
            (nelmin: 8),
            (nsw: 1000),
            (potim: 0.2),
            (sigma: 0.2) [electron_volt],
            (xc: 'pbe'),
            (kpts: [3, 3, 3]),
            (prec: 'Normal'),
            (encut: 300) [electron_volt]),
            task: local minimum

The Property parameter employed is:

prop_en = Property energy, stress ((structure: geom_pd27), (calculator: calc))

The model was executed+evaluated using in interactive-session mode:

~$>texts session -w -r -f pd27_stress-tst.vm 

The VASP calculation seems to be completed successfully, but the the interpreter somehow realizes that the property is not found. In this case the session does not crash.

Similarly, a print(prop_en.stress) statement in the same model script results cuases a much earlier crash and this other error message:

Type error: /hkfs/work/workspace/scratch/an9294-palm-project-testing/PALM-H_uptake_tsts/mod_tst/tst2/pd27_stress-tst.vm:34:7 --> prop_en.stress <--
could not find DType for type: AMMLProperty, basetype: None, id_: stress