Credit memos are instead applied as a normal payment applied against the invoice. While the integration does not currently support syncing credit memos as payments back to ConnectWise PSA, we have already received similar feedback from other partners and it is on our radar to review.
We meet every Thursday to discuss our next features and our partners' suggestions are a large part of that process. You are also welcome to add your feedback, other feature requests, and upvote ideas other Partners have mentioned on our Canny board, available here: gozynta.canny.io
See more on how we sync payments and credit memos.