1.18.1 fabric server
Graves are disappearing for players or being renamed to “herobrine” and players can’t access the graves. Players can /graves and see the grave and contents via gui still. OP can unlock the grave and break it to return contents through gui.

Photos of player in GUI and player at site of missing grave

graves-2.0.0-rc.4+1.18.1 It has happened 4 times to my knowledge in the last 24 hours. I do not have screenshot of the herobrine grave but have seen it myself. While trying to fix it I broke it somehow before getting a screenshot.

Whats your mod version? Also how often it happens? Does it require some specific situation? More info I have easier it is to replicate and fix

Well, I'm still not sure why it happended (graves lost their id?), but now it will be more lenient and not remove blocks... It can be incompatibility with some other mod, it might be bug in this one. If you can get a way to replicate it in steps I could get that fixed for sure... Closing for now