External storage doesn't show thumbnails

When accessing the external storage SMB, the thumbnails of the pictures are not displayed. It works in Nextcloud’s own directory.

  1. Nextcloud’s own directory picture:

    2.External SMB storage files:

Steps to reproduce

1.External storage SMB. Permissions work visible.
2.The project integrates LDAP user authentication.
3.The thumbnails of pictures in Nextcloud’s own directory are visible.