To reproduce bug:

• Take an entity with Interface, we will take the Horse as an example.
• Press 'E' to enter in UI/Interface.
• Change the name of Entity. (Try with a command block with some delay.

/data merge entity @e[type=donkey,sort=nearest,limit=1] {CustomName:'{"text":"Test"}'}

It can be seen that CustomName does not change.
If we leave the Menu and reopen it works.

This problem is annoying to create custom Interface Dynamics.