Andrea, can you open #1 in new window tab? I mean, when you hoover over it as you did, and the click right mouse button and then open in "new window tab". It should open. When it does, on top of the entry is a zoom icon, click that and you will see it in a full preview.
Does it work?
I do not think it is complicated.
Also, for the previews in finalization process, you have to upload design (designs), not the mock up, as CH is not buying mock up... it is for him/her to see clean and full logo design he/she is purchasing.