My raid completed Castle Nathria last night and on 4 of the bosses (same ones i completed in LFR) there was no loot available, not even anima, I thought this was a bug because I had done them on LFR but then there were two bosses we did that i didnt complete in LFR and had the same issue. there were several players in raid that also didnt receive any loot from the bosses. the setting for loot were on personal loot so this was not the issue.
In the case of anima, It drops off the boss once per week, even on different difficulties. Killing normal shriekwing and gaining anima then means you will not gain anima from heroic shriekwing in the same week.