json loading does not seem to preserve modified volume scale parameters

## Description

There is a condition where you can load from json and it doesn't properly apply the volume scale value.

## Expected Behavior

it should work! when loading any json, the proper volume scale should be applied both in the UI and in the rendered image.

## Reproduction

load file A, modify volume scale z, save to json. load another volume B, modify volume scale and save to json. then load json A. Some mixture of this sequence will cause the volume to not adopt the modified scale value.