Highlighting text on a sign causes it to override the sign background

Highlighing text on a sign causes the sign background to stop rendering and you to see what is behind the sign. In the images attached you can see the text on the sign rendering behind the highlighted text.

Steps to Reproduce:

1. Edit a sign using symbols like “_” and “█” in rows

2. Highlight text (highlighting the row of “_”s helps make it more clear)

3. ❌ Observe the text behind the sign being rendered, suggesting the sign backboard was overridden by highlighting the text.