You can try using the logic_case's PickRandomShuffle input instead of PickRandom .
You can also click the Help button in the top right of the entity properties window
https://i.imgur.com/iE7Whnr.png for more info on the IO an entity supports.
If that doesn't work (I don't see why it wouldn't, but..) you could add in a fail-safe logic_relay with a delayed Re-Firing of both itself and the PickRandom input of the logic_case:
logic_relay has a CancelPending input to cancel any not-yet-fired outputs (on delays). You could, on the breakables OnBreak output, hit the logic_relay with that CancelPending input.
Code:
logic_relay - OnTrigger - !self - Trigger - on a delay of 1 second
logic_relay - OnTrigger - logic_case - PickRandom - on a delay of 1 second
func_breakable - OnBreak - logic_relay - CancelPending
So the relay constantly re-triggers the PickRandom on the logic_case and itself again (on a 1 second delay, let's say), until an OnBreak output is fired and cancels the relay's outputs. Just hit the relay with a Trigger input to start such a sequence.