From what I can tell, this bug has existed since 4.0.18, which is almost 3 1/2 years, but that:
- It only affects the settings shown at VaultWiki Admin Panel > Settings > Notifications
- It does NOT affect the settings shown at AdminCP > Settings > Options > VaultWiki: Notifications
- The affected drop-down does have contents, but shows the phrase names instead of the phrase text. It should still be possible to determine what the drop-down choices mean from the phrase names.
This is fixed in the next release. In the mean time, use the alternate unaffected settings page described above, or use the phrase names shown to determine the best selection.