I feel like an idiot, but I can't get the changes I made to the vending machine in Deep Sea to remain the same after a sea reset, instead of resetting all the inventory. How can I make it persist properly? I can't monitor the sea 24/7 to make timely changes. NPCs at the water towers on the large map retain everything even after a wipe with a new map (even when their coordinates change), but in Deep Sea they don't remember anything. Is this solvable? Or if this is a problem with the sea, maybe it can be implemented in a future plugin update?

I believe this is already solved by the plugin, but there are 4 different Deep Sea cities, so you have to customize the vendors at all 4. Overall, that is dozens of unique vendors.

If you suspect the plugin isn't doing the right thing, you can confirm, when editing a vending machine inventory the Deep Sea, that the debug text on the top right says the data provider is a deep sea floating city entity, rather than a map data provider (map would be bad).