I found at least 7 Unknown Keys while playing Seablock. They go away when I uncheck Reverse Factory. I don't suppose this would be something easy to fix, seeing how there are like a million recipes and items in that mod.

If you are curious about them, then do this:
- install Seablock and all the other mods that it recommends so that that little mod status block shows all green lights.
- use FNEI to look up how to make liquid plastic. That's one bug.
- use FNEI again and hit the Select Item box, then use Search to look for "alien". Then choose the Intermediate Items tab. You'll see six fluids that are all Unknown Keys. If you then go back and uncheck Reverse Factory, you'll see that there should be no entries in that tab at all.

Its really too bad, as I use Reverse Factory to undo a lot of my booboos. And in Seablock, I make a lot of them.

Ah, I probably should have made this more clear under the mod settings, but what I think you're referring to (assuming they all begin with "rf" in the name), are the fluid items, which are technically labelled as "experimental" in the description of the mod setting. I never fully implemented this, since it was only supposed to be a temporary fix at the time, for the output of the recycler being blocked by conflicting fluids. Turning the fluids into fake "fluid items" allowed inserters to remove them, bypassing the blocked fluids issue entirely.

But it was more of a beta feature, just doing the bare minimum to make it work "for now", while still testing to see if it was an adequate solution to the problem, before looking into making it work properly, with labels and everything. If you don't need the functionality, and don't like seeing the unknown item labels, you can always just disable the mod setting.

I still haven't really decided if it's a feature worth properly implementing, because it is a little janky to have inserters pulling out recycled fluids as fake fluid items, but if you do actually use and enjoy the functionality, then I can look into making it work properly.

I'm kinda posting the same stuff both here and at the Reverse Factory Portal but that's ok. Umm...I unchecked the "Items As Fluids" setting and the Unknown Keys disappeared. That's good enough for me...I don't see myself being so resource poor as to be carrying around bottles of gases. Oh, and a coder friend at the Discord channel thinks the problem is actually with FNEI but you guys would know more about that than me. Thanks though.

Yeah, technically speaking, every recipe that produces multiple products (such as every reverse recipe that my mod creates) should have a name, for whenever it shows up in the crafting menu. By default, any recipe that produces only one product just defaults to the name of the product.

All of my reverse recipes are barred from appearing in the player crafting menu though (since they aren't needed there and would create a TON of clutter), and since they are made in the furnace, the recipe name also won't appear there. Within normal gameplay, the lack of reverse recipe names would never be apparent to the user, since it doesn't functionally affect how the recipes work.

FNEI simply removes the veil that hides this fact, by exposing every in-game recipe to the user. I will still need to look into this, since even the non-fluid item reverse recipes would have this issue.

EDIT: All unknown key related issues with FNEI should be fixed as of v8.2.16

tyvm