Thank you for reaching out! I am Andrew Tremblay, the Product Manager for our Listings products, and you are correct in your assumption that you running into claiming issues with having both services on at the same time for your client and running into conflicts.
If you haven’t already, I would ensure you have your account details in our platform as close to what you have captured in Yext. As well, it is always beneficial to grab a data export of your Yext accounts as a backup in the event you do need to reference them. You can find details on how to do the export here.
From there, it is best to either work with Yext, or if you have the power yourself, and have the services cancelled within Yext. Once those services are no longer active for a client, you should have no issues running Listing Sync Pro and reclaiming listings for your clients.
If you do run into any issues during this period or get stuck along the way, please don’t hesitate to reach out or to contact our support and we can help you out.