An idea has a process associated to it which has a review task in the steps. This review task appears to be assigned to a resource that does not have rights to view the task or the idea, and thus they are not able to complete the task.
CA PPM 15.x and above
We found that the process appears to be stuck at a step waiting for a "review" task to be completed. The task appears to be assigned to a resource who did not have rights to view or access the task to perform/approve it.
To resolve this issue, we had to cancel the process and then add/start that same process to the idea, which appears to be working properly now and routed the review task to the correct resource.