relation not found - How to use .fetch_related()?

Describe the bug
I've setup a ForeignKey field and appropriate model. When fetching the object I can't access the object under the ForeignKey field. Using .fetch_related says relation not found.

To Reproduce

# mymodels.py

from tortoise.models import Model
from tortoise import fields

class Preset(Model):
    name = fields.CharField(max_length=255)
    setting1 = fields.ForeignKeyField('models.Setting1', related_name='preset')
    
    def __str__(self):
        return self.name

class Setting1(Model):
    name = fields.CharField(max_length=255)
    
    def __str__(self):
        return self.name

# setup_data_and_test.py

from mymodels import *
from tortoise import Tortoise, run_async

async def init():
    await Tortoise.init(db_url='sqlite://db.sqlite3',  modules={'models': ['mymodels']})
    await Tortoise.generate_schemas()

async def add_data():
    s1 = await Setting1.create(name="Test-Setting1")
    p1 = await Preset.create(name="Preset1", setting1=s1)

async def done():
    await Tortoise.close_connections()

async def get_data():
    all_presets = await Preset.all()
    for entry in all_presets:
        print('Preset:', entry.name)
    
    await all_presets[0].fetch_related('preset')
    print(all_presets[0].setting1.name)

run_async(init())
run_async(add_data())
run_async(get_data())
run_async(done())

So when I run setup_data_and_test.py I get:

$ setup_data_and_test.py
Preset: Preset1
Traceback (most recent call last):
  File "D:\tortoise_orm_example\setup_data_and_test.py", line 25, in <module>
    run_async(get_data())
  File "C:\Python310\lib\site-packages\tortoise\__init__.py", line 688, in run_async
    loop.run_until_complete(coro)
  File "C:\Python310\lib\asyncio\base_events.py", line 646, in run_until_complete
    return future.result()
  File "D:\tortoise_orm_example\setup_data_and_test.py", line 20, in get_data
    await all_presets[0].fetch_related('preset')
  File "C:\Python310\lib\site-packages\tortoise\models.py", line 994, in fetch_related
    await db.executor_class(model=self.__class__, db=db).fetch_for_list([self], *args)
  File "C:\Python310\lib\site-packages\tortoise\backends\base\executor.py", line 585, in fetch_for_list
    raise OperationalError(
tortoise.exceptions.OperationalError: relation preset for preset not found

Expected behavior
I would expect to access the data of the FK-object. Or am I missing something here? How could I access objects under ForeignKey-fields?

Additional context
tortoise-orm: 0.20.0
OS: Win 10/x64
Py: Python 3.10.6

Start with mymodels.py and setup_data_and_test.py, then read tortoise/models.py around fetch_related and tortoise/backends/base/executor.py around the reported error. Reproduce the failure with the shown SQLite setup and verify the declared ForeignKey relation and the name passed to fetch_related. Done means the example can access the related Setting1 object without a relation-not-found error.