I created a while loop in the regroup method to search for while main nodes need to be swapped, with the following conditions:

while(right != null){
                System.out.println();
                System.out.println(toString());
                System.out.println();
                
                if(left == null){
                    first = left;
                    left = right;
                    right = last;
                    if(last != null){
                        last = last.getRight();
                    }
                }
                
                else if(left.getCategory1().compareTo(right.getCategory1()) > 0){
                    //swapping code goes here
                }

It works fine for the most part, but for some reason there's a specific condition for when the first node is null, and the head's value is higher than the next node's, where it deletes the next node, which is weird because I'm using the same conditions for both, just without the first node which is null, as shown below:

else if(first == null && last != null){//<-this condition deletes a node
                        Node<E1, E2, E3> tempLeft = left;
                        Node<E1, E2, E3> tempRight = right;
                        
                        last.setLeft(tempLeft);
                        System.out.println("1: deleted here?\n" + toString() + "\n\n");//<- toString prints I used to pinpoint where the node was deleted
                        last.getLeft().setRight(last); //<-location I pinpointed for where the node is erased
                        System.out.println("2: deleted here?\n" + toString() + "\n\n");
                        last.getLeft().setLeft(tempRight);
                        last.getLeft().getLeft().setRight(tempLeft);
                        last.getLeft().getLeft().setLeft(null);
                        
                        first = null;
                        left = null;
                        right = head;
                        last = right.getRight();
                    }

else{//<-this condition doesn't delete a node and does what it's supposed to, it's for when neither the first node or last node I'm checking are null
                        Node<E1, E2, E3> tempFirst = first;
                        Node<E1, E2, E3> tempLeft = left;
                        Node<E1, E2, E3> tempRight = right;
                        
                        last.setLeft(tempLeft);
                        last.getLeft().setRight(last);//<-this does not delete the node despite being written the exact same way
                        last.getLeft().setLeft(tempRight);
                        last.getLeft().getLeft().setRight(tempLeft);
                        last.getLeft().getLeft().setLeft(tempFirst);
                        last.getLeft().getLeft().getLeft().setRight(tempRight);
                        
                        
                        first = null;
                        left = null;
                        right = head;
                        last = right.getRight();
                    }

Am I missing something? I figured two statements written the exact same way with the exact same variables would do the exact same thing. I don't know why it does this. and it troubles me.