Since the update earlier this week the free packs every 4 hours have only been giving out cards from the neutral and adventure sets. The upgrade items have still been coming from all of the sets but the actual character cards haven't been. For the record I have finished the main game and was able to get cards from every set before the update.

The daily shop items have also been glitching, instead of updating every 24 hours they've been changing out at random.