Updating sci-hub manuscript version
A reload button does not show up anymore.

Also, this problem is likely related to storage of pre-print versions in sci-hub databases. From what I know, sci-hub only uses credentials on the first request for a paper. At that moment, it also saves a copy of the pdf and that copy is what is given as a result on subsequent requests.

So, I guess a solution to this problem has to involve updates to sci-hub's database.