An idea created in PPM Clarity 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.
This can happen if the resource assigned to review the idea does not have have rights to view or access the task to perform/approve it.
To resolve this issue, cancel the process and then add/start that same process to the idea to route the review task to the correct resource. If the resource assigned is correct, then grant the resource access to view the task.