So, I'm piddling around on a Space Age playthrough, moderately modded, and the one in question is Compact Roboport. I have the little roboports set up in a square to keep my logistic network separate from several others, and each roboport can handle 100 bots. I've got 400 bots in the network... or at least, that's what I put in there.
I watched the Total Logistic Bots dropping as they were queuing up for charging. I had just topped it up to 400, and I watched it drop all the way to 286. When I'd caught it before, it had been as low as 148. It is the second time I've topped it up. No spitters or worms are attacking the, nothing is destroying them they're just disappearing.
is this a known issue with the game or the mod, or any mod in particular? I've never encountered this before.
EDIT: I am a ding-dong. I had an inserter pulling drones out of the roboport and into a requester chest. Removed the inserter, problem solved. Derp.