I found an interesting one here.
In my rom hack, I (stupidly) rearranged the item list. When it came time to test out the warp staff, I noticed it was completely unusable. The unusable box was not checked, and all proper conditions were met. During troubleshooting, I tried using the vanilla warp staff, and it worked fine. I then copied and pasted exactly the data onto my clone warp staff, changing only the ID. Still, unusable. This leads me to believe that there is some hidden hard coding for the warp staff in FE8 that is not addressed in FEBuilder, nor can I find anything related to this specific issue anywhere on the internet. I suppose the request here is for someone here to make a patch to change the hard coding, or the FEBuilder devs to do so. It’s no biggie just to use the vanilla warp staff, but this seems to be an unaddressed issue.
Please correct me if any of my conclusions are wrong.