[BUG] Custom winrepo_dir_ng value breaks pkg.refresh_db

Description
When using a custom winrepo_dir_ng I cannot get the package list to get updated :

salt -G 'os:windows' pkg.refresh_db

windows-01:
    ----------
    failed:
        0
    success:
        0
    total:
        0

Setup
Salt master main config :

root@salt-master-01:/srv/dev/salt_states/win/repo# cat /etc/salt/master
interface: 0.0.0.0

jinja_env:
  trim_blocks: True
  lstrip_blocks: True
jinja_sls_env:
  trim_blocks: True
  lstrip_blocks: True

winrepo_dir_ng: /srv/dev/salt_states/win/repo/
winrepo_remotes: []

Salt master fileserver config :

root@salt-master-01:/srv/dev/salt_states/win/repo# cat /etc/salt/master.d/gitfs.conf 
fileserver_backend:
  - gitfs
  - roots

# ----------------- GLOBAL CONF -----------------------#
gitfs_global_lock: False
gitfs_privkey: [REDACTED]
gitfs_pubkey: [REDACTED]
gitfs_provider: pygit2
gitfs_update_interval: 60
gitfs_base: main

# ----------------- gitfs CONF -----------------------#
file_roots:
  base:
    - /srv/salt_states
    - /srv/dev/salt_states

gitfs_remotes:
  - [REDACTED]:
    - mountpoint: salt://


# ----------------- ext_pillars CONF -----------------------#
git_pillar_provider: pygit2
git_pillar_base: main

pillar_roots:
  base:
      - /srv/salt_pillars

ext_pillar:
  - git:
    - main [REDACTED]:
      - root:  [REDACTED]
      - pubkey: [REDACTED]
      - privkey: [REDACTED]

Steps to Reproduce the behavior
Try to set a custom winrepo_dir_ng in master config as well as in fileserver_root section

Expected behavior
The ability to define a custom dir where win repo files could be sync'ed

Versions Report
Minion :

windows-01:
    Salt Version:
              Salt: 3003.1
     
    Dependency Versions:
              cffi: 1.14.5
          cherrypy: 18.6.0
          dateutil: 2.8.1
         docker-py: Not Installed
             gitdb: 4.0.5
         gitpython: Not Installed
            Jinja2: 2.11.3
           libgit2: Not Installed
          M2Crypto: Not Installed
              Mako: 1.1.4
           msgpack: 1.0.2
      msgpack-pure: Not Installed
      mysql-python: Not Installed
         pycparser: 2.20
          pycrypto: Not Installed
      pycryptodome: 3.9.8
            pygit2: Not Installed
            Python: 3.7.4 (tags/v3.7.4:e09359112e, Jul  8 2019, 20:34:20) [MSC v.1916 64 bit (AMD64)]
      python-gnupg: 0.4.6
            PyYAML: 5.4.1
             PyZMQ: 18.0.1
             smmap: 3.0.4
           timelib: 0.2.4
           Tornado: 4.5.3
               ZMQ: 4.3.1
     
    System Versions:
              dist:   
            locale: cp1252
           machine: AMD64
           release: 10
            system: Windows
           version: 10 10.0.19041 SP0

Master :

Salt Version:
          Salt: 3003.1
 
Dependency Versions:
          cffi: 1.14.6
      cherrypy: Not Installed
      dateutil: 2.7.3
     docker-py: Not Installed
         gitdb: 2.0.5
     gitpython: 2.1.11
        Jinja2: 2.10
       libgit2: 1.1.0
      M2Crypto: Not Installed
          Mako: Not Installed
       msgpack: 0.5.6
  msgpack-pure: Not Installed
  mysql-python: Not Installed
     pycparser: 2.20
      pycrypto: 2.6.1
  pycryptodome: 3.6.1
        pygit2: 1.6.1
        Python: 3.7.3 (default, Jan 22 2021, 20:04:44)
  python-gnupg: Not Installed
        PyYAML: 3.13
         PyZMQ: 17.1.2
         smmap: 2.0.5
       timelib: Not Installed
       Tornado: 4.5.3
           ZMQ: 4.3.1
 
System Versions:
          dist: debian 10 buster
        locale: utf-8
       machine: x86_64
       release: 5.4.124-1-pve
        system: Linux
       version: Debian GNU/Linux 10 buster

Additional context
I tried to use this doc : https://docs.saltproject.io/en/latest/topics/windows/windows-package-manager.html
But I obviously failed, some insight would be great.

Thanks