Task sequence list is greyed out in Application Manager even though you have a task sequence and a group inside the task.
Make sure AM's service account has Operating System Deployment Manager role assigned in Configuration Manager.
Reload Configuration Manager information on the MECM Integration > MECM Settings > General settings tab.
Inspect C:\ProgramData\Recast Software\Application Manager\Logs\SCCM-Management-errors.log file and see if there are any error messages.
- If you can see an error message with status code 2147749890, follow Microsoft's instructions to solve the issue: https://docs.microsoft.com/en-us/troubleshoot/mem/configmgr/cannot-create-mdt-task-sequence.
- After you've completed the repair steps open up Configuration Manager console as a AM's service user and select Connect via Windows PowerShell. Run the following command and see if you get a list of your tasks Get-CMTaskSequence -fast | Select-object Name
- Go back to Application Manager and try Solution 2 again.