I’m not sure if it’s a bug, but it seems that obtaining the shard with the modifier " [Armour and Reduced Bonus Damage from Crits]"
https://www.lastepochtools.com/db/suffixes/AOwRgrEA
is either extremely hard to obtain, or straight out not possible to extract from armor pieces with a rune of shattering. It is listed as rare in the database and that part seems to be right.
But I was not able to extract one shard from over 50 items. Even when it only had 2 modifiers (armor included)
Might be similar to this thread:
https://forum.lastepoch.com/t/missing-affix-name-on-armor-and-crit-dmg-reduction/60662
E: after some more drops, I was able to aquire said shard through shattering runes. But yes, I can confirm, the shard does not appear in your crafting inventory.