Big Reactors are interfering with Thaumcraft essentia system. I posted on its issue page (https://github.com/Azanor/thaumcraft/issues/1499) and the comment references 2 other issues.

I don't know exactly what causes the problem, but there might be some invalid recipe in Big Reactors. (Maybe a recipe that produces oak wood ?) I don't know how familiar you are with Thaumcraft, so I'll just direct you to its author, Azanor (https://github.com/Azanor).

Somehow, I doubt this is actually a problem with Big Reactors and more likely a problem caused by the addition/removal of a mod shifting itemIDs, blockIDs or something similar.

I say this because I have precisely zero lines of Thaumcraft integration code anywhere in BR.

An explicit API usage would not be required. TC generates the essentia list - in part - by scanning the crafting dictionary and giving any unknown crafted items the aspects of its component parts.

However, as BigReactors does not include recipes for the listed items I am curious as to why the OP thinks its BRs fault?

The problem can be tested by scanning oak wood with the Thaumcraft scanning thingy. If it's broken, it will say "nothing can be learned from this", indicating that oak wood is not correctly registered in TC. If it's ok, it will show the tree essence, as per usual (or say that you have to scan other stuff first).

I tested this problem by removing mods that I have and when I removed BR, it was fixed. That is why I think it is BR's fault. Best thing to do is for someone else to test it like I described to make sure it's not a problem on my side.

Again, I would be exceptionally surprised if this were BR, as there aren't any recipes registered using Oak Wood from BR. All recipes are added via the standard recipe system.

So I did some more testing. I was wrong that it's BR's problem. Sorry about that.

Here is what I tested :

• bunch of mods + BR -> problem
• bunch of mods, no BR -> ok

That led me to believe it's BR's fault. But after some more testing :

• just TC, BR, CoFHcore -> ok

So it's not BR, the problem is one of those other mods that somehow links BR and TC to create this issue.

Again, I apologize for not doing more testing first before posting.

I did more testing and it's Thermal Expansion with Big Reactors that's causing it. So I guess the problem is with TE automatically adding some recipe based on BR.

I need an adult.

TE doesn't add any recipes based on BR. We also don't touch chests. Well not the storage kind. And not with code.

The reason BigReactors is required is because it causes FML to sort TE above Thaumcraft, something's up with the aspect-recipe-applicator.
Tracker: https://github.com/CoFH/Feedback/issues/7