Main problem I see is that the verbose output indicates a incorrect number of edges and nodes. Maybe a recursion issue? The offending edge is S233 -> S234.
Input file: b1209.dot
Output file: b1209.txt
Comments:
[erg] As a work-around, remove the constraint=false specifications. They aren't really necessary, since you've already specified that S235 and S236 are both sinks, and for some reason, they cause problems.

Simplified input:

digraph state_machine_97 {
  {
    rank=sink;
    S234
    S235
    S236
  }
  S233 -> S234
  S236 -> S235
  S235 -> S236 [constraint="false"]
  S233 -> S236
}