Here is my scenario. I am using Nintex o365. I have an AD group which is in sync with AAD. I could see this group on SharePoint site. Now I am assigning a task to this group and enabled "Lazy Approval" functionality. Workflow was able to generate the task and I could see GUID showing on task subject line. I tried to reply back with "Approved" it didn't work. Later I created a SP group and added this AD group there and assigned task to SP group. I could again see the task email with GUID but when I replied "approved" lazy approval didn't work. Now I simply added two users in my SP group instead of AD group. Both the users received the task and were able to approve using lazy approval.
My question is what is wrong if I only add AD group in SP group or just assign task directly to AD group. Is there any specific setting required at AAD level ?
AD group -- This is a universal security group with email enabled.
Note: This AD group is working fine in workflow. Group is receiving task emails and taking actions normally. Only lazy approval is having issue.