In my environment, we had a drive mounted to the "Task Handler" folder. It appeared that the mount was broken when the agent/plugins were updated. The folders were there but had no files in them. If the path to the "Task Handler" folder was removed and a drive letter was assigned to that directory, you could see the images again.
I am still battling with this upgrade, but so far I have started fresh with a new notification server and new task server, while using my existing database. There is definitely something going on with the packages that is causing problems and I am still looking into it. PXE images aren't making it over to the the boot server either, even after it was rebuilt.