Vanilla textures not showing up in Texture Selection screen after making custom texture. (2025.3)

I've searched around, but all of them are either unanswered or just don't have any relevant information.
As the title says, I used to be able to see the vanilla textures in the texture-selection screen for elements, and was about to use them for a block, but after creating a custom texture & went back to the texture-selection screen all vanilla textures disappeared, just gone.
Even after deleting the newly made texture & block I can't reference the vanilla textures.