Signs disregarding if you pressed enter when there are more than 17 characters

Usually, I press enter on the first line of a sign, to center the text vertically. However, if I end up typing more than two lines of text after that, (or, it seems that it might be a certain amount of characters, which seems to be 17?) when I exit the sign, the text that I typed will be at the top of the sign, disregarding the fact that I pressed enter at all, and putting the text there anyways. As far as I can tell, this only happens on my realm. I play on Windows 10.

This doesn't happen all the time, it seems to be somewhat random.