Those items should be grey and unusable. Blizzard disabled that scheme in WoD crafting as part of Shadowlands. They’re aware that the appearances of the incremental upgrades are no longer available because of this and will make them available for transmog some other way at some time in the future.
If you’re after the upgraded items to actually use them, Blizzard hasn’t said anything about that. I suspect the thinking is that you level out of WoD so fast there’s no point – you outlevel the expansion before you can get the crafting skill to make base items, let alone upgrade them.