When the jump key is set to the enter key :
-If the player execute a chat command, he will at the same time when the key is pressed.
-If the player is leaving the Comand Block GUI by pressing the enter key, he will jump.
When the jump key is set to the enter key :
-If the player execute a chat command, he will at the same time when the key is pressed.
-If the player is leaving the Comand Block GUI by pressing the enter key, he will jump.
This is something the devs can't change, so it works as intended.