Source from the twitter:
https://twitter.com/MyNBA2K/status/911768638805254144
This is pretty ridiculous. The event barely just started and networking issues were too much. This after scaling back the app and decreasing ways to feasibly acquire cards is a pretty big slap in the face.
Or maybe they just realized that people in RC wanted to grind out as many games as possible instead of hitting that "watch ad" button after the end of each game...