DK's have a new version of Anti-Magic Shell from a hero talent within the Rider of the Apocalypse hero tree called Horsemen's Aid. That version of AMS isn't tracked by BigDebuffs, so I end up wasting spells trying to cast into it.

I was able to test and verify that adding the line below to the DK section of BigDebuffs_Mainline.lua resolves the issue. Just add it under AMS. I just wanted to post this here so that it can be added to a future update - and maybe it will help someone else while an update is pending.

[444741] = { type = IMMUNITY_SPELL, parent = 48707 }, -- Anti-Magic Shell (Horsemen's Aid)

Thanks,
Serious the Warlock