Solved by KFrank in post #2 
              
              
                Hello Anyere! 

Unless there is something unusual about your classification 
problem, I think you should not use ignore_index for Class 0. 
Suppose you feed a Class-0 sample to your model (so target 
is 0), and your model incorrectly classifies it as Class 2.  You 
do want to tell your model not to …