There is still a cross-buy bug left:
Content bought on Xbox one or Xbox app, is not available when playing the PC version offline (without internet conection)
example: If you bought Shadow Jago back in December with the Xbox app and bought the Supreme Edition on PC, you can play all characters apart from Shago offline.
If you allready bought all seasons on Xbox and only Shago on PC, every character apart from Shago is locked when playing offline.
Thread about this issue: http://forums.ultra-combo.com/t/no-fighters-available-on-pc-in-offline-mode/7950/22