When changing the language setting in Tableau Desktop, Tableau creates new subfolders for the new language in the Repository, but still points to the original ones. This is confusing. Either move the pointers with the language setting or do not create new folders!
I recently changed my language setting from German (Tableau Desktop was automatically installed in German due to my location/system settings) to English. This cause Tableau to create an additional "Shapes" folder in my repository folder (Because I previously had it set to German, the repository folder is named "Eigenes Tableau-Repository"). But this new folder is not used by Tableau, it still uses the original shapes folder "Formen" from the German installation.
This is not a big issue since it is fairly easy to adapt, but it still took me a while to figure out why my shapes did not appear in Tableau: