This sounds exactly like you're not setting up your portrayals correctly when reloading. But without a [small and precise] code example, I can't help you much more.  Don't post the sample here though -- just mail it to me.  Also warning: I'm in Italy, so the turnaround time here may be as much as a week.

On Aug 19, 2015, at 9:14 AM, Axel Kowald <[log in to unmask]> wrote:

>> Have you properly re-set-up your portrayals in your load() method?
> Hm, yes. It calls setupPortrayals() as does my start() method.
> I tested also to create a checkpoint directly from the GUI and then
> reload it.
> If I quit and restart my GUI, also that checkpoint is black.
> But if I only quit the simulation without quitting the GUI itself, and
> then reload the checkpoint, the Portrayal shows my agents as it should
> be, but the display is frozen. I.e. if I unpause the simulation it runs
> but the Portrayal just shows the agents as they were after loading the
> checkpoint.
> axel