Ominous Vaults do not appear in the creative menu and cannot be placed with the "/setblock" command.

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We're tracking this issue in MC-270095, so this ticket is being resolved and linked as a duplicate.

That ticket has already been resolved as working as intended, which means this is not considered a bug and won't be fixed. Please do not leave a comment on the linked ticket.

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The setblock command is:

/setblock ~ ~ ~ minecraft:vault[ominous=true]

OK ! I didn't know that! What about in the creative inventory?

That works as intended as per the linked bug report