Unable to update child task status

Hello,

First time using MOSC, so let me know if I'm doing something wrong. I found 2 community discussions around this issue, but only 1 with a solution (Community Discussion ID 3369498) and, unfortunately, it isn't working for me.

I have a parent task that spawned 2 child tasks. I was able to cancel the 2nd of the 2 child tasks using debrief. The 1st of the 2 child tasks gives the following error whenever I attempt to update the status using debrief, and all of the fields are grayed out when within the SR, so I can't update it manually there, nor through the More button.