Enderman carrying wall signs, heads, or banners will not display their held block

The Bug:

Endermen holding wall signs, banners, or heads do not display their held block.

Steps to Reproduce:

• Summon an enderman who is holding a wall banner.

/summon enderman ~ ~ ~ {Health:1f,carriedBlockState:{Name:"minecraft:cyan_wall_banner"}}

• Kill the enderman.
  →  Notice how the banner is not shown in the enderman's hand
  Information:

This works with any variant of wall signs, banners, or heads.