Watch window unable to exlpore tables more than 3 levels deep?

Consider the following screenshot: <a href="http://img352.imageshack.us/img352/9507/image1fa4.png" target="_blank">http://img352.imageshack.us/img352/9507/image1fa4.png</a>
The first item in the watch window is the_maze.nodes[1], and the second is the_maze expanded to look at the nodes table. The first way shows the members of the_maze.nodes[1], while the second reports the_maze.nodes[1] as {}. Also note that the_maze.nodes[1].maze.nodes is reported as an empty table {}, however the_maze.nodes[1].maze == the_maze, therefore the nodes table cannot be empty.

The code in question:<!--c1--><div class='codetop'>CODE</div><div class='codemain'><!--ec1-->function maze()
  node"B"(0, 0)          B"BJ"            node"J"(2, 0)          R"JN"            node"N"(4, 0)
     Y"BI"      R"BD"               Y"DJ"    Y"JK"      B"JL"               B"LN"    Y"NP"
  node"I"(0, 1) Y"ID" node"D"(1, 1) R"DK" node"K"(2, 1) R"KL" node"L"(3, 1) Y"LP" node"P"(4, 1)
                R"IT"    B"DT"      R"TK"    R"RK"      B"KR"    Y"LR"      B"RP"  
     B"IC"            node"T"(1, 2)     finish"G"(2, 2)       node"R"(3, 2)          R"PS"
                R"CT"    Y"AT"      B"TH"               R"HR"    Y"RE"      Y"RS"
  node"C"(0, 3) B"CA" node"A"(1, 3) R"AH" node"H"(2, 3) Y"HE" node"E"(3, 3) B"ES" node"S"(4, 3)
     Y"CV"      B"AV"               R"AM"    B"HM"      B"EM"               R"EF"    B"SF"
  node"V"(0, 4)          R"VM"            node"M"(2, 4)          Y"MF"            node"F"(4, 4)
                                             R"M*"
                                         start"*"(2, 5)
end
local function getnode(n, m)
  m = m or maze
  return m[n] or m.nodes[n] or n
end
do
  local maze_fn = maze
  maze = function()
    local the_maze = {
      nodes = {},
      edges = {
        red = {},
        yellow = {},
        brown = {},
      },
    }
    local function add_node(name, x, y, special)
      local node = {
        maze = the_maze,
        name = name,
        x = x,
        y = y,
        idx = #the_maze.nodes + 1,
        edges = {
          red = {},
          yellow = {},
          brown = {},
        },
      }
      if special then
        node[special] = true
        the_maze[special] = node
      end
      the_maze.nodes[node.idx] = node
      the_maze.nodes[node.name] = node
    end
    local function add_edge(colour, nodes)
      local set = the_maze.edges[colour]
      local edge = {
        maze = the_maze,
        name = nodes,
        colour = colour,
        idx = #set + 1,
        from = nodes:sub(1, 1),
        to = nodes:sub(2, 2),
      }
      edge.cost = 1
      set[edge.idx] = edge
      set[edge.name] = edge
    end
    local f_env = {
      node   = function(name) return function(x, y) add_node(name, x, y          ) end end,
      start  = function(name) return function(x, y) add_node(name, x, y, "start" ) end end,
      finish = function(name) return function(x, y) add_node(name, x, y, "finish") end end,
      Y = function(names) add_edge("yellow", names) end,
      R = function(names) add_edge("red"   , names) end,
      B = function(names) add_edge("brown" , names) end,
    }
    setfenv(maze_fn, f_env)()
    for colour, edges in pairs(the_maze.edges) do
      for _, edge in ipairs(edges) do
        edge.from = getnode(edge.from, the_maze)
        edge.to = getnode(edge.to, the_maze)
        edge.from.edges[edge.colour][edge] = edge.to
        edge.to  .edges[edge.colour][edge] = edge.from
      end
    end
    return the_maze
  end
end
maze = maze()
local function pathfind_compare(p1, p2)
  return p1.cost < p2.cost
end
function solve(sequence)
  print("Solving for " .. table.concat(sequence, ", ") .. " ...")
  local queue = { {node = getnode"start", phase = 0, previous = nil, cost = 0} }
  local closed = setmetatable({}, {__index = function(t, k) local v = {}; t[k] = v; return v end})
  while queue[1] do
    local path = queue[1]
    table.remove(queue, 1)
    if not closed[path.node][path.phase] then
      closed[path.node][path.phase] = true
      if path.node.finish then
        print "Route found: ..."
        return true
      end
      local next_phase = (path.phase + 1) % #sequence
      for edge, node in pairs(path.node.edges[sequence[next_phase + 1]]) do
        if not closed[node][next_phase] then
          queue[#queue+1] = {node = node, phase = next_phase, previous = path, cost = path.cost + edge.cost}
        end
      end
      table.sort(queue, pathfind_compare)
    end
  end
  print "No route found"
  return false
end

solve {"red", "yellow"}
solve {"red", "yellow", "brown"}
solve {"red", "brown", "yellow"}<!--c2--></div><!--ec2-->Code is being debugged in a Lua 5.1.3 command line interpreter compiled from source.