Structure block contents resetting

Structure blocks will not save their contents

Steps to Reproduce

1. Place a structure block.
2. put some data into the text boxes.
3. Exit the dialogue.

Expected Results
The structure block retains the data that was put onto it.

Observed Results
The structure block resets to the state it was in when placed.

Note: The issue with command blocks, which was tracked in MCPE-158910, seems to be fixed.