Due to changes made by the WorldGuard developers, interact flags no longer apply to chests.

This means that any unlocked chests you may have placed are no longer protected by an interact flag and can be looted by anyone in absence of a chest-access flag!

Make sure to lock all your chests and change your town flags to deny chest-access to nonmembers (if not nonowners) to keep your and your town residents' items safe!

You can read more on the topic of flags here.