By any chance, syncronization using Agent to SQL isn't available?
Thank you for contacting our Skyvia Team!
Skyvia has not released full functionality for Agent connections yet.
At the moment, Agent connections can be used in Skyvia Query and Connect, and are available for Import, Export (as a Source) and Replication packages (as a Target).
We are working on support for Agent connections in Synchronization packages at the moment.
For Synchronization packages, only the connections created with Direct mode are shown for now.
We are looking forward to hearing from you, should you have any questions.