My snapdir was already set to visible, so nothing there revealed anything. However, following the link to the wiki page "http://zevo.getgreenbytes.com/wiki/pmwiki.php?n=Site.SnapshotBrowsing"
Where it says it's mounted on demand (on cd) is what made me realize the issue. I must not have tried a combination of snapdir=visible AND cding into the dir to do an ls. I probably just checked with ls from a different dir !!