EDIT: Strongly looks like these items are once per toon and if you deleted it too bad. Workaround is to use an alt that you’re sure hasn’t killed any of the mobs. The items all drop in one or two kills.
These are white items from Hollowfall that are soul bound and are combined to create illusive-kobyss-lure. Since it 11.0.7 there appears to be a problem with them dropping.
Scanned all the places I could have stored a soul bound item many times and I don’t appear to have them.
And they don’t appear to drop.
Is there a hidden quest you can test for them having dropped? Guessing they dropped and got deleted and now wont drop or there is bug.