Text on placed signs disappears when you leave the vicinity of the sign and come back. It seems like this is tied to the chunk containing the sign being unloaded and reloaded.

I observed this problem on Realms, but a similar issue has been reported for BDS (BDS-15571). The issue may be related to multiple other issues with 1.17.3x: MCPE-143738, MCPE-143772, MCPE-143785, REALMS-5898 among others. It's possibly related to other text-handling issues seen with 1.17.3x, such as the (apparently resolved) issue where signs would lose formatting (§) and carriage-return characters.

I've observed this problem on the iOS and Xbox clients. It is consistently reproducible.

Steps to reproduce:

1. Place a sign and enter text (see my exemplar text below). It appears as expected as you enter it.  
2. Exit the sign editor, confirm that the sign still appears as expected.
   
3. Leave the area, and travel far enough away that the chunk where the sign is placed is no longer loaded. Traveling far enough away that the area around the sign doesn't render is usually far enough.
4. Come back and observe the sign.

Expected results

The sign looks like it did when you left.

Actual results

The sign is blank when you return:  

Exemplar text

§f<--

§bTunnel 1 East

§fPlace One

§fPlace Two