Having a weird bug here. I can't find any reference to it anywhere else; there's some discussion of a patch at some point that messed up the controls but I'm certain that's not my problem.

I start the game. It works fine, for a short while. Sooner or later (and generally pretty soon; too quickly to finish any level besides the first one), the "Contaminate" mutation stops working. The uses remaining for Contaminate shows a number greater than 0, I click on a human (it highlights green), but nothing happens. Even more oddly, while this doesn't diminish the visible uses remaining for Contaminate, it's clear that it does actually reduce the game's view of how many Contaminates I have left, because after trying this X times, where X is the number of Contaminates left, humans start highlighting red instead of green, and picking up more Contaminates refreshes the visible counter to what the game thinks it is.

Once it stops working, Contaminate never does anything in that level again. Quitting to main menu and starting again resets this, but it still stops pretty soon (sometimes on the first click; sometimes after 2-3).