I thought that the game took the data from the server directory before loading those contained in the server.jar file.

Since it does not work, I deleted the "loot_tables" folder from the server.jar archive and tried to put the "loot_tables" folder in different places :

ServerRoot\loot_tables
ServerRoot_world_\data\loot_tables
ServerRoot\assets\minecraft\loot_tables

(See an example on the picture)

Nothing works, what should I do to use a folder "loot_tables" located outside the archive "server.jar" ?

Thank you
PS:
Obviously if I modify the files in the archive "server.jar" it works !