When you enabled New Bed Screen (Experimental) toggle, and then enabled any resource packs, it will cause the screen to uses the old button textures even though the resource packs didn't modifying any button textures, relates to MCPE-178701

Steps to reproduce:

1. Download the resource packs attached in this report, or just simply use any resource packs you've own and then enable it
2. Enable the New Bed Screen (Experimental)
3. Enter any world, then go sleep

Expected results:
The button uses the new textures

Observed results:
The button uses the old textures