For a comprehensive list of other examples of issues with item positions in the Creative inventory, click here.

All tickets associated with item placement in the Creative inventory are valid for cases introduced in 1.16 and later as per this comment. Exceptions exist, which are valid for their own reasons.

The bug

Amethyst blocks are not grouped with any of the blocks one may expect them to be grouped with. They are not grouped with diamond or emerald, despite amethysts, diamonds and emeralds all traditionally being precious stones, nor are they grouped with quartz blocks, despite amethyst being a variety of quartz.

The recommend fix for this would be moving all four families of blocks next to each other.

How to reproduce

1. Open the Creative inventory
2. Locate Block of Amethyst in Building Blocks
3. Locate Block of Quartz in Building Blocks
4. Locate Block of Diamond in Building Blocks
5. Locate Block of Emerald in Building Blocks
6. Note that there is a considerable distance between these items