https://github.com/obsproject/obs-studio/issues/2788

is_it_group_item_question_mark.lua

local obs = obslua

--- name of a scene item
local source_name = ''

--- get the name of the current scene
local function current_scene_name()
  local source = obs.obs_frontend_get_current_scene()
  local name = obs.obs_source_get_name(source)
  obs.obs_source_release(source)
  return name
end

--- find the named scene item
local function find_scene_item()
  local source = obs.obs_get_source_by_name(current_scene_name())
  if source then
    local scene = obs.obs_scene_from_source(source)
    obs.obs_source_release(source)
    if scene then
      local items = obs.obs_scene_enum_items(scene)
      for _, item in ipairs(items) do
        local item_source = obs.obs_sceneitem_get_source(item)
        local item_name = obs.obs_source_get_name(item_source)
        -- print(item_name)
        if obs.obs_sceneitem_is_group(item) then
          local group = obs.obs_group_from_source(item_source)
          local group_items = obs.obs_scene_enum_items(group)
          for _, group_item in ipairs(group_items) do
            local group_item_source = obs.obs_sceneitem_get_source(group_item)
            local group_item_name = obs.obs_source_get_name(group_item_source)
            if source_name == group_item_name then 
              print('found: ' .. group_item_name) 
             end
          end
          obs.sceneitem_list_release(group_items)
        end
      end
      obs.sceneitem_list_release(items)
    end
  end
  scene_item = nil
  print('done')
  return false
end

function script_description()
  return [[Repro of obs.obs_sceneitem_group_enum_items() bug
Open a scene with a Group and select the name of a Source within it {workaround version}]]
end

function script_properties()
  local props = obs.obs_properties_create()
  local source = obs.obs_properties_add_list(
    props,
    'source',
    'Source:',
    obs.OBS_COMBO_TYPE_EDITABLE,
    obs.OBS_COMBO_FORMAT_STRING)
  for _, name in ipairs(get_source_names()) do
    obs.obs_property_list_add_string(source, name, name)
  end
  return props
end

function script_update(settings)
  source_name = obs.obs_data_get_string(settings, 'source')
  find_scene_item()
end

--- gets a list of source names, sorted alphabetically
function get_source_names()
  local sources = obs.obs_enum_sources()
  local source_names = {}
  if sources then
    for _, source in ipairs(sources) do
      -- exclude Desktop Audio and Mic/Aux by their capabilities
      local capability_flags = obs.obs_source_get_output_flags(source)
      if bit.band(capability_flags, obs.OBS_SOURCE_DO_NOT_SELF_MONITOR) == 0 and
        capability_flags ~= bit.bor(obs.OBS_SOURCE_AUDIO, obs.OBS_SOURCE_DO_NOT_DUPLICATE) then
        table.insert(source_names, obs.obs_source_get_name(source))
      end
    end
  end
  obs.source_list_release(sources)
  table.sort(source_names, function(a, b)
    return string.lower(a) < string.lower(b)
  end)
  return source_names
end