Forms Designer in Workflow Task Form is missing the List Attachments Form Control
While designing a Task Form in Workflow Action, like Assign Flex Task, the Attachments list column Form Control is not available. A user responding to a task request is unable to view any attachments in the list. Although you could check the checkbox of "Include list item attachments" in the Configure Action of Assign Flex Task, having the list Attachments form control right on the workflow task form will be much convenient.

-
Allan Helbling commented
It will be more convenient for sure, but it will also need to have the hability to push tasks attachments to the main item.
At the moment those attachments are lost.