We are having problems getting a bundle to launch on anything other than "Refresh".

Specifically we would like to have the bundle launch on "Device Boot".
I have enabled the distribution schedule to run on Device Boot, and have ticked the Install Immediately and Launch Immediately.

Before restarting the WS, I refresh Zenworks Agent.
I check that the bundle can be seen (it is both available and the "effective" box is ticked).

When I restart the WS, there are no errors (in event log) and the bundle has not done it's work at all. If I check the zdm messages log (set to verbose) I can see the action was invoked and no errors attributed to it:
[18] [] [Bundle] [] [Performing scheduled event on item: TestBundle] [] []

Any advice?