Hi,
I had looked around and couldn't find this info. But after playing around I found a solution and wanted to share to give back.
I drag and drop messages from outlook to my task list comment field. It creates a hyperlink direct to the message which is great so I don't have to hunt.
I don't know what version or update but the links that were being created were wrong and didn't link to the source.
There seems to be two ways to create hyperlinks. I don't know why the difference but only one works for me to get back to my messages from ToDoList.
When dragging and dropping the message into the comments field, hold down the shift key before dropping.
This creates a link with a very specific identifier. A plain drag and drop creates a link with a human readable type of path. And that one does not work.