OUR FIX
Eventually we learned via DESCRIBE EXTENDED, that the table had lost its Location path in production environment. Querying via the development environment to the production catalog  the location path  was still visible.
Solved the issue (with the right Manage rights on the materialized views) by deletion of the views from bronze, silver to gold and refreshed the DLT again. After that the location path of the table was visible in PRD as well. I have not found the rootcause of the corrupted locationpath for this specific table in our PRD environment.