[Bug]: salt --preview-target doesn't show minion connected through salt-syndic

What happened?

I expected that salt --preview-target '*' test.ping would show every minion connected, but it doesn't seem to evaluate minions connected through a salt-syndic server.

Type of salt install

Official deb

Major version

3006.x

What supported OS are you seeing the problem on? Can select multiple. (If bug appears on an unsupported OS, please open a GitHub Discussion instead)

debian-12

salt --versions-report output

Salt Version:
          Salt: 3006.23

Python Version:
        Python: 3.10.19 (main, Feb 17 2026, 23:32:03) [GCC 11.2.0]

Dependency Versions:
          cffi: 2.0.0
      cherrypy: 18.10.0
  cryptography: 46.0.5
      dateutil: 2.8.1
     docker-py: Not Installed
         gitdb: Not Installed
     gitpython: Not Installed
        Jinja2: 3.1.6
       libgit2: Not Installed
  looseversion: 1.0.2
      M2Crypto: Not Installed
          Mako: Not Installed
       msgpack: 1.0.2
  msgpack-pure: Not Installed
  mysql-python: Not Installed
     packaging: 24.0
     pycparser: 2.21
      pycrypto: Not Installed
  pycryptodome: 3.19.1
        pygit2: Not Installed
  python-gnupg: 0.4.8
        PyYAML: 6.0.1
         PyZMQ: 23.2.0
        relenv: 0.22.4
         smmap: Not Installed
       timelib: 0.3.0
       Tornado: 4.5.3
           ZMQ: 4.3.4

System Versions:
          dist: debian 13 trixie
        locale: utf-8
       machine: x86_64
       release: 6.12.88+deb13-amd64
        system: Linux
       version: Debian GNU/Linux 13 trixie

Start by reproducing salt --preview-target '*' test.ping in a setup containing a salt-syndic server, then trace how preview-target evaluates minions across that connection. Done means the preview includes every connected minion, including those reached through salt-syndic, while preserving the existing behavior for directly connected minions.