Signs won't display the whole message typed in

On my Minecraft Realm, I type a message on a sign and after hitting escape, I see the message slowly appear on the placed sign as if I'm typing it. But after it finishes typing out the whole message, the letters begin to delete as if I'm pressing backspace until only a few letters remain. For example, I tried "Do not trade these villagers" and the final sign showed "Do not" only.