On Client portal the preview of the document is not the pdf so it is just completely bugged. Margins are not the correct ones, sign does not appear... etc. That does not look professional at all. If a client access the client portal but the signed document only appears if downloaded but not on the preview that is the thing that is loaded on first place, what sense does it make?

Also, why do some quotations get displayed in a different way than others? Why is that? Check the attached images. 

I belive this last one is as it should be done taking into account it does not preload the buggy invoice with out the sign and correct margins