Fold line is not visibles

[sbushmanov]

Neovim version (nvim -v | head -n1)

NVIM v0.10.0-dev

Operating system/version

Ubuntu 22.04

How to reproduce the issue

I would like to see those beautiful fold lines; however, for some reason they don't show up. My config:

return {
  -- UFO Folding
  {
    'kevinhwang91/nvim-ufo',
    event = "BufRead",
    dependencies = {
      'kevinhwang91/promise-async',
      {
        "luukvbaal/statuscol.nvim",
        config = function()
          local builtin = require("statuscol.builtin")
          require("statuscol").setup({
            relculright = true,
            segments = {
              { text = { builtin.foldfunc },      click = "v:lua.ScFa" },
              { text = { "%s" },                  click = "v:lua.ScSa" },
              { text = { builtin.lnumfunc, " " }, click = "v:lua.ScLa" },
            },
          })
        end,
      },
    },
    config = function()
      vim.o.fillchars = [[eob: ,fold: ,foldopen:,foldsep: ,foldclose:]]
      vim.o.foldcolumn = '1' -- '0' is not bad
      vim.o.foldlevel = 99   -- Using ufo provider need a large value, feel free to decrease the value
      vim.o.foldlevelstart = 99
      vim.o.foldenable = true

      local ufo = require("ufo")

      local handler = function(virtText, lnum, endLnum, width, truncate)
        local newVirtText = {}
        local suffix = ('  %d '):format(endLnum - lnum)
        local sufWidth = vim.fn.strdisplaywidth(suffix)
        local targetWidth = width - sufWidth
        local curWidth = 0
        for _, chunk in ipairs(virtText) do
          local chunkText = chunk[1]
          local chunkWidth = vim.fn.strdisplaywidth(chunkText)
          if targetWidth > curWidth + chunkWidth then
            table.insert(newVirtText, chunk)
          else
            chunkText = truncate(chunkText, targetWidth - curWidth)
            local hlGroup = chunk[2]
            table.insert(newVirtText, { chunkText, hlGroup })
            chunkWidth = vim.fn.strdisplaywidth(chunkText)
            -- str width returned from truncate() may less than 2nd argument, need padding
            if curWidth + chunkWidth < targetWidth then
              suffix = suffix .. (' '):rep(targetWidth - curWidth - chunkWidth)
            end
            break
          end
          curWidth = curWidth + chunkWidth
        end
        table.insert(newVirtText, { suffix, 'MoreMsg' })
        return newVirtText
      end

      ufo.setup({
        fold_virt_text_handler = handler
      })
    end,
  },
}

Any help is appreciated!

Expected behavior

Visible fold lines

Actual behavior

Fold lines are not visibles:

[kevinhwang91]

Type za under  line.