`selection_strategy = "row"` is broken for `builtin.buffers()`

[mroavi]

Description

selection_strategy = "row" broken for builtin.buffers()

Screencast.2021-12-02_selection_strategy_bug_new.mp4

This used to work fine as shown here: #828

Neovim version

NVIM v0.6.0-dev+558-g3ba800f15
Build type: RelWithDebInfo
LuaJIT 2.1.0-beta3

Operating system and version

Manjaro Linux x86_64 - Kernel: 5.10.79-1-MANJARO

checkhealth telescope

telescope: require("telescope.health").check()
========================================================================
## Checking for required plugins
  - OK: plenary installed.
  - WARNING: nvim-treesitter not found. 

## Checking external dependencies
  - OK: rg: found ripgrep 13.0.0
  - OK: fd: found fd 8.2.1

Steps to reproduce

See video above.

Expected behavior

The selection should stay on the same row after pressing "m".

Actual behavior

The selection resets and goes to the first row after pressing "m".

Minimal config

vim.cmd [[set runtimepath=$VIMRUNTIME]]
vim.cmd [[set packpath=/tmp/nvim/site]]
local package_root = '/tmp/nvim/site/pack'
local install_path = package_root .. '/packer/start/packer.nvim'
local function load_plugins()
  require('packer').startup {
    {
      'wbthomason/packer.nvim',
      {
        'nvim-telescope/telescope.nvim',
        requires = {
          'nvim-lua/plenary.nvim',
          { 'nvim-telescope/telescope-fzf-native.nvim', run = 'make' },
        },
      },
      -- ADD PLUGINS THAT ARE _NECESSARY_ FOR REPRODUCING THE ISSUE
    },
    config = {
      package_root = package_root,
      compile_path = install_path .. '/plugin/packer_compiled.lua',
      display = { non_interactive = true },
    },
  }
end
_G.load_config = function()
  require('telescope').setup({defaults = {selection_strategy = "row"}})
  require('telescope').load_extension('fzf')
  -- ADD INIT.LUA SETTINGS THAT ARE _NECESSARY_ FOR REPRODUCING THE ISSUE
end
if vim.fn.isdirectory(install_path) == 0 then
  print("Installing Telescope and dependencies.")
  vim.fn.system { 'git', 'clone', '--depth=1', 'https://github.com/wbthomason/packer.nvim', install_path }
end
load_plugins()
require('packer').sync()
vim.cmd [[autocmd User PackerComplete ++once echo "Ready!" | lua load_config()]]