This plugin, like all others that attempt to perform some specific function on wipe, relies on Oxide calling a particular hook the first time the server makes a new save after a wipe. If this didn't work, that probably means the plugin was not loaded at that particular moment. A common reason that a plugin wouldn't be loaded after a game update is because it was broken immediately following that update, but that seems unlikely in this case since nobody has reported issues with the plugin since the game update this week.
The only other reason I could think of is that Oxide itself was not even loaded immediately post wipe. If that was the case, then other plugins that perform a function on wipe would also have been affected, although you may not have noticed because the effect may have been more subtle or the stale data may have had no effect, depending on the plugin. This is a pretty interesting theory, as it could be pretty easy to encounter by restarting the server automatically without applying an Oxide update first, so it could lead to issues with potentially lots of plugins, so I wonder if there is any way Oxide could handle that better.
For the immediate concern, I am planning to add a requested feature soon to allow wiping specific players' backpacks, so I'll probably throw in a server/admin command to wipe all backpacks as well, which could be useful to server owners if and when this kind of thing happens in the future.