Rearranging tracks in show builder works once, then errors

## Description of Issue

Rearranging tracks when working in the show builder works fine for the first track one moves, but any subsequent ones result in a red “error writing” message at the top of the screen and guidance to reload the page. This gets a little painful. Issue surfaced using Firefox on a Mac.

## Possible Solution and/or Approach

Unsure as to the technical reason for this behavior, so not really able to suggest fixes. Apologies.

## Additional Comments

I'm Iris Berkeley on air if I can be helpful discussing — mail@irisberkeley.com