Ive also found that if i pause the game for a prolonged period of time, the dissapear, and i cannot complete the level. Also, that glitch you described sometimes happens when i slash sword robots, with absolutly nothing to support the upper torso, yet they still try to kill me
I've recently come across this during testing. It's filed under critical right now, since it seems to happen consistently on the interim build. Hopefully we can sort out these odd Spidertron behaviors for the upcoming patch. Thanks for the report!