I hope you are very well today. Getting help on this is not urgent. After spending a lot of time trying unsuccessfully to get Snapshot to work, I've found an alternative that doesn't use it. I'm sending in what I thought might be a bug.
Trying to transfer a site to a dev vagrant site on my laptop, Snapshot repeatedly failed because it claimed tables were not existent in the target site. I removed a few of the offending tables from the source, but it started to become an infeasible was to resolve it.
Having Snapshot fail to back up the site due to nginx 405 errors and being unable to transfer managed backups to a new server is making it very difficult to use.
Let me know if you need to see the source site or any snapshots.