Using upload for the first time I was unable to see the payslips so just thought I would pass on this information (which many of you will probably already know) having recently spoken with a Sage Guru.
On doing the Payroll Year End, change the process date to 5 April using the Wizards click onto Payroll Year End, on selecting P60's there is an option to 'upload' (the same as for payslips).
However when I logged into the Document Portal and having clicked onto P60's nothing appeared - this was simply because the year had been updated to 2019/2020 which is on the right hand side near the top of the screen so simply needed to change to 2018/19 and there were the P60's.
Hope this helps one or two users of Sage