some bases not existing in game?

i was trying to farm fine bracers for chancing maligaros, but this base doesnt seem to exist in game. also none on trade. never seen it drop, even deactivated my lootfilter and went to lvl 47 zones.... nothing. i dont understand the logic here....

Noticed the same with trying to find 3 dragons helm base type. Solid mask(?) i think

My guess as to why they aren't in the game is they're base types that we'd first start finding in acts 4/5/6 and have been held back to finish their design and ensure it matches whatever themes are in the later acts.

100% a guess though.