Set Item Drop Issues

EeuorT

I did public dugeon boss runs to complete The Rift, Deshaan, Rivenspire, Greenshade and Grahtwood sets. Each of those I got all types of set item drops and each drop was always a new set item I didnt have yet. Then and only then did I get drops for a set item I already have. Glenumbra and Stonefalls stopped giving new set item drops and only give ones I already got before. Which left me with Stonefalls has 2 set items left that wont drop and Glenumbra has 3 set items left that wont drop. So I did what online shows as how to collect set items.
"Delve bosses drop a waist, foot, or unique item piece. Overland bosses drop a head, chest, leg, weapon, or unique item piece. Public dungeon bosses drop a shoulder, hand, weapon, or unique item piece. Chests at World Events, most commonly Dark Anchors drop a jewelry set piece." None of those gave the set items I still needed. So I went to the locations for the unique set items and the boss didnt drop the set item theyre supposed to which is one I still need. I killed Lilou because I needed Bloodthorne's Touch head piece and she didnt drop Bloodthorne Lilou's Curative Coif.
After trying all that an Undaunted quest sent me to a Stonefalls delve. Killed the delve boss and got the Bloodthorne's Touch head set item I still needed... killed it again and it dropped the boots set item I needed... delve bosses dont drop set item head pieces. I still have 3 set items left in Glenumbra. Tried the same things for there and none give the drops I still need.
So "Delve bosses drop a waist, foot, or unique item piece." and "Public dungeon bosses drop a shoulder, hand, weapon, or unique item piece." didnt apply to my game. Got a delve boss set item head drop and got all types of set item drops from Public dungeon runs.

virtus753

Named items do not respect curation and are often dropped by mobs who do not have the generic equivalents in their normal loot tables.

If Lilou cannot drop a generic head piece, she should never drop a generic hat and will not be guaranteed to drop the named one just because you're missing it in your collections. You can, however, continue to farm her for the named item, and when you bind it it will count towards your set collection.

There is a Stonefalls delve boss who can drop the named helm for the Shalks set. Again, that's dependent on RNG and independent of curation and normal loot tables.