we have encountered something weird. One delivery email with attachment (ex. picture1.jpg) is succesfully sent. If you copy that delivery template in the workflow and edit new copied delivery template before workflow is saved in order to add another atachment (ex. picture2.jpg) then after execution only second attachment is sent.
In case you first save workflow and then edit copied delivery to add another attachment then everything works fine and both attachments are sent.
Any idea, why is first attachment lost in that case?
If I understood you correctly you copied the activity of type delivery from a workflow (or another workflow) to the same workflow(or another workflow). In my knowldege it is not recommended by Adobe to do such a copy but it is still possible. I suppose that the reason why it is not recommended is exactly because of these situations where you cannot rely on the configuration being properly copied. In your case, when you do not save the workflow, the copied delivery is not saved in the database (mData field of the workflow) and the configuration is based only on a context at the interface level. Most probably when you add a second attachment the first one from the context is overwritten. You can check the context by doing a right click -> Edit XML in the details of the workflow to see the whole xml definition (including the temporary context). Please keep in mind you can do that when you open the workflow in a separate tab dy double clicking on it.
Hope that this is helping you understand better how ACC is working 🙂