Glad to see you were able to solve the issue.
The Snapshot Manager unfortunately relies on the entries in the .vmsd file rather than a real live view, and if the contents of the .vmsd file are deleted, you will not see the snapshots in the Snapshot Manager anymore. What you may consider is to schedule a Snapshot Reporting PowerCLI script to run on a daily basis and send email alerts (you can find several samples on the Internet), or use RVTools either interactively, or in batch mode as a scheduled task with email reporting.
André