Sign text disappears shortly after you exit the GUI

SOMETIMES, when you type in text in a sign, very shortly after you exit the GUI, all of the text disappears. It disappears on all devices including your own.
Expected result:

The text is there.

Observed result:

The text is not there.

Steps to reproduce:

Type in this: §9§lTO X-ST TERMINAL (A lot of other messages disappear too)

Exit the GUI