Hi there, I'm testing out Skyvia as a connector between a Dynamics CRM 8.2 on-premise instance and Constant Contact. 

I've successfully created the synchronization package and I'm able to push data (firstname, lastname, email) from my Dynamics CRM instance to Constant Contact, but when I make an update to a record's email address in Constant Contact the change does not sync back to Dynamics CRM. I get an error of "No record found for the specified lookup condition."

It looks like there's a GUID stored in Constant Contact as the record ID. I've tried adding a field in Dynamics CRM to store the Contact record GUID created by Dynamics, then mapping that to the ID field in Constant Contact, but when the record syncs from Dynamics to CC it does not seem to write the GUID from Dynamics to Constant Contact. The contact in Constant Contact seems to retain the CC internal GUID.

I've also tried updating my mapped ID field in Dynamics to store the Constant Contact GUID. I manually copied the CC record GUID from the error message into the mapped field in Dynamics CMR, but the sync job still fails to find the matching record using that mapped field and ID. 

Is there any documentation on how to map between Dynamics and Constant Contact such that updates can flow from CC back to Dynamics? 

Any ideas for what I could try?