hi folks,
i had the same problem with my brand new PC where i had to install FS again. After doing so a not countable times by deinstalling / installing / waiting for 150GB to be downloaded and again no marketplace accessable, i now found the relaxing and frustrating (because of loosing so much time and frustration) easy, simple and straight forward SOLUTION…
simply go to
options (1) - general (2) - data (3) - online-functionallity (4)
and activate this option
it seems, that 99,9% of your user settings are stored inside your online account, but not this one. So i missed to crosscheck that for one week now and lost so many time…
after i have activated this option the marketplace becomes accessible after a few seconds again 
hope that will save some time for everybody with this problem
so long and always have lift under your wings