Light blocks do not show their texture when the player holds them but instead show their texture when the player holds a barrier block.
The hitbox of the Light block is unaffected, it only appears when the player holds a Light Block.
Structure Blocks are unaffected.
Already reported: https://bugs:mcjang.com/browse/MCPE-163653
Other reports weren't showing up in the search function until after I had viewed them at least once. (Active report found by another user)