BPM - File Types Allowed for Upload/Approval Attachment Error

We have a requirement to restrict file types attachments in BPM Worklist Approvals. We have come across multiple possible solutions, but continue to receive an error when we try approving/rejecting with an attachment. This error is shown in the first screenshot. I have also shared how the Task's access is configured in the second screenshot. Has anybody ever received a similar error, if yes, how did you resolve this issue? Could there be another security component involved? Or possibly an issue with the approval rule itself?