Text disappears from sign when "forest" is written on it in my realm

Got a bizarre one for ya; can't find this problem anywhere so I wonder if it's just our realm that's acting up, lol. I can't write the word "forest" on a sign. It makes all the text disappear from the sign. I can write "fores" and "orest" but not "forest"; however, if I first write "dore" and then on the next line "forest", the sign does hold its text. Doesn't work when I type "sore". Very strange.

It holds true even when reconnecting and restarting the game so it doesn't seem to be a visual glitch. It also doesn't seem to be a problem with the game directly, because I can write "forest" just fine in single player. I have no resource packs installed.

Here's a video (unlisted) of it happening: https://youtu.be/Fu1pX4o6Kzg

Weirdly the one time I got smacked by a zombie the text did stay on the sign.

Anyone else?

*Apparently it's not limited to the word forest, i tried typing "5100x" and it also disappeared