The following error usually means that the OAuth2 token that Yoxel holds is not valid anymore and a connection to Highrise/Basecamp is denied. This happens when you've changed your 37signals password, the token that Yoxel Portal holds got invalidated.
Basic realm="Application" : HTTP/1.1 401 Unauthorized
HTTP Basic: Access denied.
The solution is to re-authorize Highrise/Basecamp access in Yoxel:
- Open the Highrise/Basecamp service, make it inactive, save
- Open again, make it active, save