Hi Mojang, I added MCPE-123617 a week ago detailing similar problems with Marketplace not working. It was closed as a duplicate of this issue but I have put on there details of some information which may be relevant that I have not seen in the above comments of this issue. Please can you take a look at MCPE-123617 just in case there is something in my notes that may be of use in fixing this ... been going on for a year now! Cheers.
Still not fixed for me! Original problem (1 account can access marketplace and 2 can't) still persists nearly 2.5 years after I raised a separate issue (which was closed as duplicate of what has become this issue)
Clearing Marketplace Cache on problem account made no difference.
Problem still shows red exclamation mark with "There is an error with your account ....."