The following solution worked for me:

1. In the body of the work flow email, position yourself where you want the link to go
2. Then click on the edit hyperlink button in the top right of the window
3. In the address, paste in the URL to your EditForm for example: https://domain.sharepoint.com/Lists/mylistname/EditForm.aspx?ID=
4. Then select the string builder button (...) to open the string builder window.
5. In the string builder window position your cursor at the end of the line (just after ID=) then press the "Add or Change Lookup" button.
6. Select Data Source = "Current Item" and Field from source = "ID"

Then ok that and save and publish.

The following solution worked for me:

1. In the body of the WorkFlow email, position yourself where you want the link to go
2. Then click on the Edit Hyperlink button in the top right of the window
3. In the address, paste in the URL to your EditForm for example: https://domain.sharepoint.com/Lists/mylistname/EditForm.aspx?ID=
4. Then select the string builder button (...) to open the string builder window.
5. In the string builder window position your cursor at the end of the line (just after ID=) then press the "Add or Change Lookup" button.
6. Select Data Source = "Current Item" and Field from source = "ID"

Then ok that and save and publish.