My entire base is on a single surface, so yes they're all being deposited into the depots on the same surface I'm attempting to build on. The items aren't anywhere in the logistics network according to the "L" menu in-game, so they're not in any storage chests somewhere. My game is heavily modded, so it's possible it might be some sort of edge case/mod conflict, but given that it happened to the vanilla selector combinator, I'm not so sure. I never saw any items in any of the chests they were getting placed in, yet there's a discrepancy of ~700 items that are completely missing. My production graphs show 700+ crafted, ~20 placed, zero in storage, and zero consumed/destroyed.