It was fixed hours ago in the new version 1.3.9.0 , its all 1080p now.Earlier today I saw it at 1920x1080, now (at 6:34 pm EDT) it is 720x480.
Sorry I don't have a log as I have downloaded it already earlier at 1080p.
As far as I know 4k video are encrypted with advanced L1 method and I saw none apps that can download without re-encoding. The are "people with access" to encoding algorithm that sell decoding tool, surely for big bucks) So 1080 is maximum you can get nowNice cover art Lowpro. Wonder which tools people are using to get 4K.