The server starts fine when using the default bedrock level and is visible to join from the app. Changing to other levels copied from a single player game works fine as well, the server can be started and the world is visible to join from the app.

After copying a large world to the server (attached), the server appears to start correctly but the server is never visible from the Minecraft app - NOK.

It was expected that the server would be visible in Minecraft.