Hello AJ,
this setting cannot be changed for a product type/transaction type if such deals already exist.
This leads to inconsistencies as you already encounter it.
If you want to use 00002 in the future, you will have to use a different or new transaction type/product type combination. If there are not too many deals with this transaction type, you might also think of reversing them and then recreating them with the new processing category.
Best regards,
Marie