Apparently since the last update it is no longer possible to pick our thumbnail when the workbook is connected to a published datasource.
Result: Every workbook uploaded to Tableau Server with a user filter of some sorts returns 'User specific view' thumbnails.
Well I was, and still am perfectly capable to decide for my own what kind of thumbnails our users should, could and need to see, no matter the datasource.
Especially for our internal users it does not matter if they see the general thumbnail (You can hardly read the numbers anyway).
90% of our users use the thumbnail as identification of the view.
According to security bulletin ADV-2019-007: Partial information disclosure in thumbnails
Correspondence with Technical Support of Tableau:
"As mentioned, based off of the dynamic filters option Tableau desktop cannot generate a thumbnail as a different user once the data source is published. So in this case the option to generate the thumbnail as per the security bulletinwould be lost.
The thumbnail generated in the circumstances outlined above as a result will be 'User specific view'. This is in the interest of not displaying information to users outside of their defined group.
As generating the thumbnail as the publisher is not currently built into the product we can submit a feature request for this and one of the best options for providing feedback would be to submit the request to our community Ideas board http://community.tableausoftware.com/community/ideas."