People's Army of Sonoma

I have just tried to Imbue several pieces of armor that I probably made over 2 years ago, and it says: "The special materials in this item are too old to survive the imbuing process."
Can I take it that we can't imbue anything that we made before Imbuing launched? If that is the case, we need to think twice before buying a piece of armor or a weapon, from a player-vendor, that we want to Imbue.

I don't think it's that you cannot imbue items made before SA, but instead has something to do with some other properties of the items. But I am not sure what those properties are.