In the first case, it will be looking for James_BobRelations by default; you can change that behavior:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<James_BobRelation>().MapSingleType().ToTable("TableNameHere");
}
Basically the default behavior is to pluralize your object and infer the table name from that. IE it will infer a name of Sausages for a class named Sausage.