Fulltextsearch doesn't add new documents from external cifs/samba storage

Hi,
may be this is just a configuration issue.
I'm using nextcloud/owncloud already for a long time at least since version 6. Now I'm on Nextcloud 13.0.1 and recently (on version 12) changed from Nextant to elasticsearch.

Indexing of local files stored in Nextcloud itself works as a charme. But when it comes to indexing files on external mounted smb shares new files are not recognized as new ans thus not indexed.

Just a few remarks about my installation.

OS: Ubuntu 16.04 (i7-3773 @3.4 Ghz, 32GB RAM)
DB: Postgres 10
Webserver: Nginx

Elasticsearch 6.2.3 in Docker container with indices on SSD

Nextcloud cron selected for background job processing (not Ajax or webcron)

crontab
*/15  *  *  *  * www-data php -f /var/www/nextcloud/cron.php
*/17  *  *  *  * www-data php -f /var/www/nextcloud/occ files:scan --all --quiet

systemd daemon for live indexing
[Unit]
Description=Elasticsearch Worker for Nextcloud Fulltext Search
After=network.target

[Service]
User=www-data
Group=www-data
WorkingDirectory=/var/www/nextcloud
ExecStart=/usr/bin/php /var/www/nextcloud/occ fulltextsearch:live
Nice=19
Restart=always

[Install]
WantedBy=multi-user.target

All fulltext apps on most recent version 0.61 except Full text search - Files which is on 0.60 due to the lack of a newer version

Any help would be greatly appreciated.

Many thanks in advance.

Start by reproducing the difference between local files and files on the external SMB share using the mentioned occ files:scan --all --quiet and occ fulltextsearch:live commands, while checking the Elasticsearch worker configuration. Done means newly added external-share files are detected and indexed, with the relevant failure or configuration cause identified.