This is by far the most painful problem I am dealing with right now.
My really hacky (and not pleasant viewing) fix is to add a state to the parent dynamic panel called loading.
At the beginning of the the interaction that resizes the nested panel I raise and event called "startLoading" and then raise another event at the end of the event wait for 100ms called "endLoading".
In the page where the master is inserted, I then set the startLoading raised event to set the parent panel to the loading state and then the endLoading raised event to set it to the desired state.
This works but causes some page jumping and is extra work for something that really ought to work, anyway.
Hoping for a fix for this soon. It will save me a lot of man-hours and help me to produce prototypes which are much more acceptable to my clients.