Yup, that first step is really important. I had this issue for several days and just solved it using step 1. I had a problematic account with the Fix Now button showing...only it wouldn't fix! The issue turned out to be an old Work/School account I was given when helping out at an on-line event a month or so back. Unknown to me was that this account went away sometime after the event concluded and I forgot I still had it as a connected account. The Fix Now button did NOT show me this account (it was no longer valid and available), so it couldn't fix it. The light bulb came on when I found the account still listed as connected under Settings > Accounts > Access work or school. The instant I disconnected this account from Windows 10, the Your Phone Companion app finished it's connection with my Android phone and things are normal again.
That helped me!
I think, that is in general the problem with this stucking at 60%. The windows app is getting stuck, not the phone. IIn my case, it was getting stuck while trying to enter my outlook account. Since I had two additional accounts on my PC (work and school) it couldnt do it. Deleted both other accounts, reseted smartphone app on the pc and it worked right away!
Crazy Microsoft. I mean, how the f. and why the f. cant they solve sth like this?