In my fusion setup the empty dt fuel cells are collected in a buffer chest before being used to create new fuel cells. I started with an almost full chest, but now there is about 60 empty cells inside. I have not observed one of the reactors not returning an empty cell, but where else could they have disappeared to?

Otherwise great mod, really enjoying it :)

Did you try pressing L to see the logistic network storage?

No empty cells in there. I am using loaders to unload them from the reactor, but that should work right?

The only problem I know of with loaders is sometimes they are put down in the wrong orientation. Maybe the empty cells are stuck in a belt if the loader is not putting them in the chest.

I don't think so. The reactors and their support is not a very big setup and have almost no belt connections to the rest of the factory so I am pretty sure I would have spotted 400 empty cells somewhere. I will have an extra look just in case :)