Missing interpolation_start Field for Display Entities

The Bug

Display Entities Missing interpolation_start.

What I expected to happen:

adding interpolation_start: -1 would allow for block animation over Duration.

What actually happened:

Interpolation_start can't Be Added thus disabling display animating.

Steps to Reproduce:

1. summon Display Entity [text, block, or item]
2. Display nbt of Entity going to be Altered via /data get entity @e[type=!minecraft:player,limit=1,sort=nearest] ()
3. Observe (Missing interpolation_start: -1000L Field)
4. Set nbt to Properly See Given Display Entity via /data merge entity @e[limit=1,sort=nearest,type=!player] (for text_display use {item: {text:' {"text":"Test"}

   '}}; for block_display use {block_state: {Name: "minecraft:tnt"}}; for item_display use {item: {id: "minecraft:tnt", Count: 1b}})

5. Change nbt of any Transformation Value via /data merge entity @e[limit=1,sort=nearest,type=!player] (for Nbt use {transformation: {translation: [1.0f, 0.0f, 0.0f]}} or {transformation: {translation: [-1.0f, 0.0f, 0.0f]}} as Examples)
6. Set/Add nbt Valuse for interpolations via /data merge entity @e[limit=1,sort=nearest,type=!player] {interpolation_start: -1, interpolation_duration: 20}
7. Observe (Entity doesn't Take a Second to Travel, insted Teleporting)
8. Display nbt via /data merge entity @e[limit=1,sort=nearest,type=!player]
9. Observe (Missing interpolation_start: -1 Field)

Affected Entities: text_display, block_display, & item_display.