This is a strange bug but when a potion effect is applied in creative mode and your taking a chest out of the creative menu a black bar appears. This only works with Chest, Trapped Chest and Ender Chest from what I tested.

Replicate

• Be In creative
• Apply an effect (Any will Do)
• Look up chest in creative inventory
• grab Chest, Ender Chest or Trapped Chest (Only grab one because grabbing 2 fixes it)

I provided an Image down below

Update: It also works with Banners and Beds (Any Color)