Sporadic JSON parsing error with remote datasource

Ahoy!
 
We've experienced some erratic issues with the pivot component fetching and populating JSON formatted report data from a remote datasource.
 
Our implementation generally looks something like this:

$('#pivot-container').flexmonster({
  report: {
    dataSource: {
      type: 'json',
      filename: '/path/to/report.json'
    },
    // ...
  }
})

 
It appears to "break" while walking over and parsing the JSON response, printing this to the browser console:

Uncaught SyntaxError: Unexpected token : in JSON at position 9
  at JSON.parse ()
  at b.AB (flexmonster.js:1094)
  at Ne (flexmonster.js:1093)

 
Setting breakpoints to pause it immediately beforehand shows it passing a string that reads like this into JSON.parse:

"city_id":9, /* ... */ "is_primary":1}

Note the absent leading curly brace ({) - obviously that's what's causing JSON.parse to throw the above exception, but I can't figure out how that's happening - the response body is correctly formatted.
 
It's very difficult to reproduce and almost seems random:

• I've been able to get it to repeat with a very specific dataset, but even then it's sporadic and only happens ~50% of the time.
• I also can't reproduce it in Firefox - it seems exclusive to Chromium-based browsers.
• The problem disappears if I insert or remove a record from the dataset.

 
I thought this might be related to compression or content length: our server gzips the payloads at transfer, but disabling compression works. Fetching and parsing the data separately and passing it into the pivot component's updateData() method also works. Neither of these workarounds are ideal as our datasets can often be enormous.
 
I don't know that this problem is within your scope, but I figured I would reach out in case you have any ideas! Thanks in advance, and sorry for all the words!