I already have a case open with support, just posting here for moral support 🙂
We upgraded to RU6 over the weekend and the upgrade process was really quite smooth. We have over 20K clients and by yesterday afternoon, all but about 2500 had updated. (Many of those are spare devices sitting on shelves or old hardware). The issue we have discovered is during our image jobs after we boot into windows, we install the Altiris Agent and sub agents via scripts in the unattend.xml. Run script tasks execute just fine, however quick delivery tasks do not actually start the command line associated with the quick delivery task.
We see in the agent logs that the client picks up the QD task, downloads the files, and then adds the task to the run schedule, but the command line never executes. Support has said they saw this exact behaviour before but it was addressed in RU4.
I will keep everyone updated with what we here from support, they have taken the issue to the dev team.