Very same thing happened to me earlier tonight. Got too friendly with the Glass Dagger, died, and my subsequent gravestone dropped none of my items.
EDIT: Normal Blood Magic sacrificial dagger does not do this. Only the Blood Arsenal Glass Dagger does this, for me.
FTB Beyond, 1.11.0, latest versions of Blood Magic, Blood Arsenal, Gravestone, whatever those are as of this post.
I'd be more inclined to give more detailed information but this apparently has been an issue for a year, across multiple versions.
Glass Dagger of (self) Sacrifice is severely bugged and ought to be disabled until (if?) this is fixed. Luckily, I always play with cheats enabled because I expect stuff like this. I can't imagine the frustration playing on a server and permanently losing end-game items because of this. I'd probably just give up on that game. It's all the more obnoxious because the Bleeding effect, at random intervals, deals a random amount of damage - combined with losing all your stuff, it's almost a slap in the face.
The only proper bug report I've seen of this is a year old and closed. Something should be done about this, finally, please.
