I'm on NixOS and slowly working through neovim config.

I have treesitter installed with all grammars and it's set up in lua. When I run :TSymbols, it pops open a window showing -----treesitter-----, but no symbols are shown from the (python) code I have open.

All of the setup is put in place by the config flake I'm using, but I don't think there's any additional stuff to add for symbols to work. The treesitter section in the resulting init.lua from nix looks like this:

require('nvim-treesitter.configs').setup({
      ["context_commentstring"] = { ["enable"] = false },
      ["highlight"] = { ["enable"] = true },
      ["incremental_selection"] = {
        ["enable"] = false,
        ["keymaps"] = {
          ["init_selection"] = "gnn",
          ["node_decremental"] = "grm",
          ["node_incremental"] = "grn",
          ["scope_incremental"] = "grc"
        }
      },
      ["indent"] = { ["enable"] = false },
      ["refactor"] = {
        ["highlight_current_scope"] = { ["enable"] = false },
        ["highlight_definitions"] = {
          ["clear_on_cursor_move"] = true,
          ["enable"] = false
        },
        ["navigation"] = {
          ["enable"] = false,
          ["keymaps"] = {
            ["goto_definition"] = "gnd",
            ["goto_next_usage"] = "<a-*>",
            ["goto_previous_usage"] = "<a-#>",
            ["list_definitions"] = "gnD",
            ["list_definitions_toc"] = "gO"
          }
        },
        ["smart_rename"] = {
          ["enable"] = false,
          ["keymaps"] = { ["smart_rename"] = "grr" }
        }
      }
    })