From what I can see in Research Queue I have all the researches that are needed for Promethium to unlock but it shows that it's blocked. How do I diagnose this? Same with Abyssal Diving gear. In that case i've got Nuclear Submarines and Quantum Processor. Any advice much appreciated!

Hmmm, very interesting.. it appears that Promethium Science Pack has 2 prerequisite technologies that don't appear in the tech tree when you select it. The lesser one being the Interstellar Science Pack (requires 2 planetary techs before you can begin to research it, so you probably already have it), but the more pertinent one being Operation Iron Man, of all things (it simply enables cargo drops on Rubia).

If you haven't visited Rubia yet, that might be the tech you're missing (the only way to even check during runtime is by printing it in the console). I'm not entirely sure why those 2 techs specifically don't appear in the list, maybe there's a limit on the number of visible prereq techs? Which is odd, considering how utterly massive the tech tree appears when Promethium Science Pack is selected...

Oh, I think I figured it out. Operation Iron Man is part of the visible tech tree, but it's a direct requirement for Aquilo, Paracelsin, and Maraxsis, each of which has a science pack that is already required for Promethium. Intersteller Science is also a requirement for the same 3 planets, plus Tenebris. I'm assuming these prereq techs can't show up twice in the tech tree, so they just appear in the spot where they have the most connections.

That actually brings up the question of how you already have the other prereq techs, if you haven't visited Rubia? Since Operation Iron Man is a requirement for Aquilo, Fusion Reactor requires the Aquilo science pack, and itself is a requirement for Promethium Science? Unless you're just missing one of the trigger techs? Mineral Science, Time Science, Bioluminescent Science, and Biter Egg Handling can't be manually researched, only triggered by crafting (and capturing an enemy spawner, for that last one)

As for a solution to the visual oddity.... the Promethium Science Pack is being modified by 9 other planet mods (at minimum!) in this pack alone. Assuming... yes, Muluna adds the Interstellar Science Pack, and appears to be the one adding it as a prereq for Promethium Science (despite already being a prereq for Aquilo, whose Fusion Reactor tech is already a prereq for Promethium Science). Rubia... appears to be doing the same thing, adding one of its techs as a prereq to the Promethium Science.

So they should probably stop doing that, since it's superfluous (though at the end of the day, the visual oddity shouldn't affect anything, since they will both be getting researched at some point for the other prereq techs)

Thanks for taking the time to look at this and if I can do anything to help you debug it just let me know. I have all of the Rubia sciences. I also have Mineral, Time, Bioluminescent, Hydraulic, Galvanization, Biorecycling, Biofusion. The only think I cheated on was Battlefield science. I was playing on peaceful and i couldn't get the enemies to do whatever it was they had to do to let me get the first bits of data to start the process. If the answer is simply that you can't play in passive mode then by all means sorry for wasting your time. Once again, I really appreciate your time.

Ahh, that might be the problem then; the Lithium Battery is a requirement for Promethium Science, and it appears in the tech tree for me as a prerequisite, so it's not hidden or obfuscated in any way. Lithium Battery requires the Battlefield science pack from Castra, so that may have been your issue after all.

To clarify the rest, you need: Mineral Science (from Igrys), Time Science (from Janus), Bioluminescent Science (from Tenebris), Biter Egg Handling (after Gleba), Deepsea Research (after Maraxsis and Aquilo), the Fusion Reactor (after Aquilo and Paracelsin), and the Lithium Battery (after Castra and Aquilo). In addition, these should be naturally unlocked as you progress towards the other packs, but both Interstellar Science and Operation Iron Man are requirements (I found this out since I was using commands to unlock techs directly, without researching any of their prereqs)

On paper, Castra science seems pretty straightforward, just requires tapping into a Gunpowder mine, a Millerite mine, and a Sulfide vent? Then processing those base resources into a Forge, and then... oh, Battlefield data packets? I think I remember seeing this in a playthrough/review video, but they should be naturally spawned from these "Data Collector" buildings scattered around the planet? From what I remember, the items should just appear on the ground next to the Data Collectors, with a random chance to be a data packet.

If you use Ctrl+F4 to open Debug Settings menu, then check "show-debug-info-in-tooltips" (about halfway down the list, after the multiplayer checkboxes), hover the cursor over the Data Collector buildings, you should see their spawning cooldown ticking down constantly. This appears to still function even with "Peaceful Mode" enabled, though it does not work when you "Disable enemies" entirely (the buildings appear, but the spawning cooldown stays at zero)

And in case your game has some different requirements for your Promethium Science, you can use the following command to check the list:

/c game.print(serpent.block(prototypes.technology["promethium-science-pack"].prerequisites))

I figured it out! I thought interstellar science was researched when it was only unlocked. Sorry for all the confusion!