Hi, Helen.
I can't be that specific. All three systems were syncing, unmonitored, and suddenly I notice a Hazel alert that there are new files in the folder's .sync/Archive folder. The 42,168 files deleted (this time) had not been modified in years; this particular folder is an asset library from which images, fonts, etc. are linked and accessed, occasionally added to, but rarely edited or modified.
Sent.
Yes. We're restoring these and hoping they don't spontaneously get deleted again. As you might expect, when 42k files are deleted from an in-use asset library, all work halts until those files are restored, which takes hours using Mac's SyncTwoFolders.