Form fields sometimes not being correctly applied to agreement despite v6 API indicating it was

I have an intermittend issue where every once in a while the form fields added to my agreement using the PUT /agreements/{agreementId}/formField API do not correctly display despite the response from that API indicating they were.  Specifically I've seen the response from the API indicate that form field X was sent to adobe, however it is never displayed.

Here is how I create the agreeement:

1. Call POST /api/rest/v6/agreements/ to create the agreement in AUTHORING state with members in the participantSetsInfo 
2. Call GET /api/rest/v6/agreements/{agreementId} to get the id's of my participants
3. Call PUT /api/rest/v6/agreements/{agreementId} with form fields.  I fill out the assignee fields based on the participan'ts id's in the prior step

My form field payload is quite large and is usually about 4500 lines of pretty print json.

There is no reliable way for me to reproduce but the error rate we're experiencing is unacceptable as this used in a real production system.  

Here are the two specific issue's I've seen so far:

1.  No form fields at all display on the pdf
2.  Form fields display but the fields with an assignee do not allow the user to fill them out

Example broken agreements:

1. CBJCHBCAABAAxN1nUvLwa0AqNcJDKcJbEiCUgTi8YxCk 
2. CBJCHBCAABAAfOYrolaIalb7uKRgUgaUCzli0ra0iuFn

Both of those agreements are experiencing issue #2.  If you view the document there are form fields in it but if you call GET /agreements/{agreementId}/formFields it returns nothing.  This seem impossible.  Usually we get back the form fields for an agreement after it was created.  

Questions

1. Is this a bug with the v6 adobe API? 
2. Am I encountering issues because I'm sending so much form field data? 
3. Can I improve the way I'm creating the agreement so that this issue doesnt happen? 
4. Would it help if I add a 1 or 2 seconds sleep in between creating the agreement and uploading the form fields?