Problem adding source to nvim-cmp

Question

I am having difficulty adding a source to nvim-cmp: I am failing to add cmp-luasnip-choice to nvim-cmp. I have listed my minimal configuration below.

A test Lua snippet with a ChoiceNode basically works, but the completion does not.

The command CmpStatus results in:

# ready source names
- luasnip
# unavailable source names
- luasnip_choice

I have tried various options (neovim stable/nightly with minimal configuration: lazy, colorscheme, cmp, LuaSnip, cmp-luasnip-choice, cmp_luasnip) without success.

The installation of cmp-buffer or cmp-calc worked without any problems.

Registering the source manually

lua require("cmp").register_source("luasnip_choice", require("cmp_luasnip_choice").source.new())

resulted in

# unavailable source names
- luasnip_choice
- luasnip_choice

Any ideas?

lazy.nvim configuration:

return {
    "hrsh7th/nvim-cmp",
    dependencies = {
        { "L3MON4D3/LuaSnip",
            opts = function()
                require("luasnip.loaders.from_lua").lazy_load({ paths = { "./snippets" } })
            end
        },
        "saadparwaiz1/cmp_luasnip",
        "L3MON4D3/cmp-luasnip-choice",
    },
    version = false,
    event = { "InsertEnter" },
    config = function()
        local cmp = require("cmp")
        local luasnip = require("luasnip")

        vim.keymap.set({"i", "s"}, "<C-e>", function()
            if luasnip.choice_active() then
                luasnip.change_choice(1)
            end
        end, {silent = true})

        cmp.setup({
            snippet = {
                expand = function(args)
                    luasnip.lsp_expand(args.body)
                end,
            },
            sources = cmp.config.sources({
                { name = "luasnip" },
                { name = "luasnip_choice" },
            }),
            mapping = cmp.mapping.preset.insert({
                ["<CR>"] = cmp.mapping.confirm {
                    behavior = cmp.ConfirmBehavior.Insert,
                    select = true,
                },
            })
        })
    end
}