American servicemen in unmarked grave in Cork

This evening I was watching a docu-drama on the "Spanish Flu" pandemic of 1918-1919 in Ireland when near the very end there was a mention of three American sailors who died of the flu and were buried in an unmarked grave in a small graveyard in Queenstown, now Cobh, Co. Cork. I want to know more. Why were they buried in an unmarked grave? Why not shipped home for burial as all other fatalities in Queenstown were? (I think the family had to pay for repatriation at that time.) Why weren't headstones sent over by the Navy to mark these sailors' graves?

I'm not sure if there's any difference for those who served in the Navy and those who were in the Army, but I know veterans of the American army who later lived here and died here can have their graves marked with a standard military issue headstone. Who pays for that, I don't know.

Anyway, I was surprised to learn that men who served in the Navy, who died while serving, lie in an unmarked grave. That should be remedied.