Sorry for the rapid series of bug filled updates. Here's what happened:

I for the life of me could not figure out why the monsters would sometimes go invisible. So I wrote code that would try really hard to render them even if their animation was in a corrupted state. The new code immediately produced crashes without crash logs in version 0.9.3.01 and so in 0.9.3.02 I updated the code to catch those crashes with a proper crash log and also improved my rendering without art code....which immediately crashed again. Turns out I was looking in the wrong place because the issue wasn't with the artwork or the animations of monsters at all, but with their pathfinding. A very well hidden bug with monster pathfinding was attempting to normalize a zero vector (an impossible mathematical operation) and the result was that monster position data was becoming corrupted with a NaN value (not a number) and since we do math on that position for the sake of rendering the NaN was spreading to other variables making the monsters invisible.

This same pathfinding was used in other places and so this fix should probably result in other fixes such as fixes to bugs having to do with your crew members doing strange things while following you.