SGP and how it handles a lost star from PHD2

There are many times that I get a long way through an exposure only to find it fails due to a cloud. Ideally what I want is to be able to cover the scope when the cloud approaches and settle for a say a 25 min exposure that should be 30min. But what happens is PHD2 tells SGP it has lost the star and the sequence ends.

I thought that setting in Auto Guide "Restart current frame when guider distance >" would control this, but when not ticked it still stops the current exposure.

I am not referring here to any form of recovery, just the ability to salvage the current frame. Perhaps I have not got a setting right somewhere?

Thanks,

Mike