I am unsure what this ATO is referring to?
EDIT: Oh, I'm guessing it's All The Overhauls Modpack? I've heard that one referred to as ATOM, not just ATO, mb.
I do remember getting a report about that on an unrelated thread, and one of the posters there mentioned this:
For the record, you've nailed it on the issue with ATOM. It basically turns the mini assemblers into the electronics assembly machines from Bob's mods (higher speed, smaller footprint, but limited recipe selection), so it depends on not just the old functionality but a fairly specific set of settings within it.
They need to either set the dependency to the previous version of mini machines (v9.3.28), or they're going to have to update the code that references any mini machine recipes or removed settings. Any balancing changes made to the entities themselves are fine (though they might also have to unhide the entities from the factoriopedia, since I have them hidden, to make it easier to check the modified stats)