The folder in question is THE Deleted Items folder. I want to move flagged messages to that folder. There's no quotes in the folder name.
If you make an action to Move To: Deleted Items (no quotes), instead what happens is a DELETED_ITEMS folder is created and the message moved there.
If you make the action Move To: "Deleted Items" (name is quoted), then the rule ... until this latest build ... correctly moved the message to the actual Deleted Items.
This is a screenshot of the rule that worked until the latest update.
The "Add Text to Subject" works, the Move doesn't.
Note though, all my rules are created under Domain Settings, so the rules apply to all users. I don't have any separate rules for individuals. I'm not certain if that's a factor (though I'll try to set up an individual rule to confirm). It's possible if you're trying to repro via an individual account rule, it's possible you won't.