GoogleFrog Why do my Crabs just wiggle in and out of armor state, allowing full damage to them? This cost me so much this game.

I have now watched the replay and was incorrect. The hax from this patch appears to be holding.

You gave the Crab an Attack Move order towards the edge of a cliff with no vision. As enemy units became visible (due to firing) your Crab would stop and fire. As they stopped being visible it would unpack and move forwards. I would recommend you not use Attack Move on Crab in such situations.

Looking a bit more closely the HLT is hidden and revealed at weird times. Perhaps there is a minor bug with the aLOS reveal code when the LOS is at patchy as it is. In any case, you can't expect 100% reliability from Crabs when you give them Attack Move orders towards area with very patchy LOS coverage.