Seems some items like Napalm Artillery Shells from Bob's Warfare and Express Loader Furnaces from Loader Furnace are not recyclable despite previous versions allowing it. Both items do require liquids as part of their crafting (150 and 120 respectively).

(sorry about the delay, been busy recently)

Hmmm... I see the issue... but don't really understand why this is happening. I'm not sure if I can fix this?

The item goes through the recycling process, but simply doesn't complete, and the machine is effectively jammed until it's mined up and placed back down, which is not good. The last time this happened, it was back when Factorio's algorithms would prevent item results larger than their stack size, so it could be that there is a liquid "stack" limit being reached here?

EDIT: It doesn't look like fluids have "stack sizes" (at least the vanilla ones don't), so I'm definitely not sure how to fix...

Some extra Info:
The Express Loader Furnace uses Lubricant and the Napalm Artillery Shells use Napalm.
Other items that don't recycle: Rails, and Deuterium Fuel Cells (Bob's Mod, not sure which one. Has Deuterium as a liquid ingredient)

If there's two liquids, that probably wreaks all sorts of havok with the new liquid system. You could force auto-barrel liquids, if they could be barreled (maybe add steel barrels in a separate slot or hell, give them for free). Only other thing I can think of is setting output pipes per ingredient order, but factorio normally checks/sets fluid pipes on recipe change, so there would have to be background shenanigans, that the machine changes recipes (which could be what you very well do now). Fluid output boxes could be in a fixed order instead of rotatable, which wouldn't be difficult considering many oil buildings are fixed order. If flamethrower fuel was ever recyclable, that used to take two fluid ingredients. Copy+paste.

Have they actually implemented any fluid changes recently? I'm pretty sure the multi-fluid recycling worked properly in 0.17, until some point. Could it have been broken when they did the oil changes?

I could take a look at how oil does things; if the oil recipes have information baked into them, or if the oil refinery itself is setting the pipe limitations.

And no, I dont know how it worked, but Factorio used to just output the two fluids into a certain pipe. Dont know how it decided this, but it just worked without any special handling on my end.

I assume early on in .17 they made the fluid changes. I didn't play until after it became stable. I just know it's super annoying and dumb now (the pipe controls what the machine can do,.. what the heck, seriously?!?). I can safely assume they broke things for stupid reasons, so just copy and paste what they're doing now is what I'd do.

Sorry to resurrect this thread, but I think I found the issue. The max limit of fluid to sit in the output slots of Reverse Factory 4 is 100

That is very odd, didn't think there would be any kind of fluid output limit. Hmmm...

I recently came across a mod that touched upon some rather interesting things about fluid_boxes, which led me to the below fluid_box explanation image. Vanilla oil refineries (and my recycling machines) have their base_level defined as 1, and I assume their default base_area and height are also 1.

So I just added a line to each fluid_box on the recycling machines, changing their base_area to 10, which appears to have increased their total storage amount from 100 to probably 1000, which hopefully should be enough for most fluid-based recipes? Though not sure how this will affect flow mechanics (among other pipe mechanics that I still need to solve in another thread...)

Anyways, potentially fixed as of v7.0.9

Just tested v7.0.9 and it seems that the problem is now fixed.