1. `copy_cache` in `models.py` recursively copies the caches to environment, 
2. which in
```python
def _compute_related(self, records):
        """ Compute the related field ``self`` on ``records``. """
        others = records.sudo() if self.related_sudo else records
        if records.env != others.env:
            copy_cache(records - records.filtered('id'), others.env)
        values = list(others)
        for name in self.related[:-1]:
            values = [first(value[name]) for value in values]
        for record, value in zip(records, values):
            record[self.name] = value[self.related_field.name]
```
3. copies failing cache values that have been produce previously by this line:

`models.py : def _prefetch_field()`
```python

        try:
            # THIS ONE
            result = records.read([f.name for f in fs], load='_classic_write')
        except AccessError:
            # not all records may be accessible, try with only current record
            result = self.read([f.name for f in fs], load='_classic_write')
```
I checked it's exactly the same `FailedValue` object, which is later accessed without intent (not refreshed) by the fact that the buggy environment is copied to sudo (and not refreshed).


super(Many2one, self)._setup_attrs(model, name)
        
        if not self.delegate:
            self.delegate = name in model._inherits.values()
    def _update(self, records, value):
        """ Update the cached value of ``self`` for ``records`` with ``value``.
        This is used to reflect the assignment ``value[name] = records``, where
        ``name`` is the inverse field of ``self``.
        """
        records._cache[self] = self.convert_to_cache(value, records, validate=False)
    def convert_to_column(self, value, record):
        return value or None
    def convert_to_cache(self, value, record, validate=True):
        
        def process(ids):
            return record._prefetch[self.comodel_name].update(ids) or ids
        if type(value) in IdType:
            return process((value,))
        elif isinstance(value, BaseModel):
            if not validate or (value._name == self.comodel_name and len(value) <= 1):
                return process(value._ids)
            raise ValueError("Wrong value for %s: %r" % (self, value))
        elif isinstance(value, tuple):
            
            return process(value[:1])
        elif isinstance(value, dict):
            return process(record.env[self.comodel_name].new(value)._ids)
        else:
            return ()
    def convert_to_record(self, value, record):