If you're bulk categorizing and you do a manual categorization, Books auto-creates a new categorization rule. When you save that rule it runs the rule against your transactions and creates the "Recognized" transactions list from the rule matches. You can then select the matches and choose to categorize them all.
All fine and good so far.
The problem is that if you simply add a matching criteria to an existing rule and save it, the rule is not executed and no "Recognized" transaction list is created.
Why would one care?
The way it is now, you're creating a separate rule for virtually every similar transaction. So let's say I have an expense account named "Software Expense" which includes a number of recurring software subscription payments. To keep things organized, I'd likely create one rule named "recurring software subscriptions" and have a criteria line for each software product that matched on description.
The way it is now, if I have 15 software subscriptions, I have to have 15 rules to process them (yes, I know this is only for existing uncategorized transactions not newly imported transactions).
Two ways to approach the fix:
1) Simply support manual running of rules against all or selected transactions.
2) When saving a rule after editing, run the rule, just like what happens when you save a new rule.