Signs and books, when placed or edited, will replace the current text with the last text edited.

Steps to recreate

1. On Xbox or PlayStation (the only platforms we've been able to recreate this bug) create a new creative world.
2. Place any sign on the ground, type out text
3. Place a second sign on the ground, the text previously typed will be automatically put onto this second sign.
4. Edit that text to something different 
5. Click to edit the first sign, the text is replaced with the updated text from the second sign.