Strangely enough. I've been getting the pills now since the latest update. I've also gotten to about 1000% item boost, so maybe it's just absurdly rare? Or the game literally prevents it from dropping unless you reach a specific drop rate? I kinda don't doubt that's the case. As in all honesty by that point of the (current 1.3.17) game you've all but fully beaten it. I've also noticed the deployment line has been shrunk back a bit. So that it's not at the literal edge of the screen.
The sandbags also actually drop them as well now as the enemy description says they should. Instead of just being minor annoyances.