Error when trying to merge duped email address contacts - One from SFDC one from Marketo
Im trying to merge contacts with the same email address. The contacts were originally added in Marketo, they have since been added in SFDC, creating duplicates in Marketo.
Selecting the SFDC contact as the lead as per below

I get the following error - "Merge failure, unable to perform merge operation in natively-synced CRM."

Do we need to update settings on the SFDC end to allow the merge to take place? If so what?
Thanks!