Did you try running netlify deploy --build as your command?
Could you confirm if Svelte is being detected as your framework inside the CLI? If not, you might have to specify some settings in your netlify.toml. If all this is related to a single codebase, that we’ve asked for in this: Svelte app. Using svelte-routing. Click on a route, displays fine. Click refresh - broken link. Fix? - #13 by kreollc, we can take a better look and let you know once you share the repo.