All it's contents also disappear. Conrail Tombstone has an API for it if that is of any help.

It's a pretty popular mod, with over five million downloads.

@AngleWyrm10 You should localize which mod is preventing this, because it works properly with only tombstone & smartBackpacks (you can make the test), there's already a compat for smartBackpacks, and it auto-equip a bag when you click the grave (check your back too ;) ).
NB : as precision, during theses tests, the inventory of theses bags was never lost.