You can see through a transparent object like "stained_glass_panel" or "stained_glass" and some blocks are not seen through this.

If you do not understand very well here I leave some images:

https://gyazo.com/1c757761c49b1187ec707729641cca2b

https://gyazo.com/7c07e22726014340561f963ad28de981

What I expected to happen was...:
See blocks

What actually happened was...:
Transparent block

Steps to Reproduce:

List of objects that I found that this happens to them:

Chest, trap chest, block slime, glass, glass panel, sulker box, ender chest, banner, head, sing, bed, string

1.  Place one of the objects in the list
2.  Drop stained_glass_panel or stained_glass
3.  Look through the object drop