Mongoose .find() returns an empty array when searching by enum field

I have this schema:

const SoundSchema = new Schema({
    name: {
        type: String,
        required: true
    },
    minFrec: {
        type: Number,
        required: true
    },
    maxFrec:{
        type: Number,
        required: true
    },
    minInt:{
        type: Number,
        required: true
    },
    maxInt:{
        type: Number,
        required: true
    },
    category: {
        type: String,
        lowercase: true,
        required: true,
        enum: ["Hogar", "Naturaleza", "Conversación", "Ocio", "Lugares", "Ciudad"]
    }
});

And I am trying to create this route to show all my items that match a certain category:

app.get("/sounds/:category", async (req, res) => {
const sounds = await Sound.find({ category: 'Ocio' }).sort({ name: 'asc'});
res.render("sounds/category", { sounds });
});

It does not work (returns an empty array) but it works if I filter by something without “enum” (name, minInt, etc).

I have done other routes that work, and I can find those items in mongo (db.sounds.find({category: "Ocio"})).