The bug:

Light emitting blocks and items have a special "glowing" visual effect when being held or placed on an item frame. However, certain items such as campfires don't do the same. See both pictures for a comparison (Education Edition items not included).

Notes: Items with the enchanted glint will glow on item frames, but not while dropped/in hand.

Update: Some glowing items were added after the creation of this report, I'll be adding them to the description:

Glows properly:

1. Small Amethyst Bud;
2. Medium Amethyst Bud;
3. Large Amethyst Bud;
4. Amethyst Cluster.

Should glow, but doesn't:

1. Glow Ink Sac;
2. Glow Item Frame;
3. Glow Berries;

Doesn't glow and might be intentional:

1. Amethyst Shard;
2. Spawn Glow Squid.