Sort issue is fixed now in App Store release. Apple is really weird and never approved the TF release that would have come before that, not sure what's happening there.
Sorting by new posts works now too.
As far as crashes, these might be fixed now because of some issues we had with the loading of lists.
For the record, we had to overhaul two major parts of the app to maintain performance - both state management and the UI library. The entire app relies on these two things, and there were some performance issues with the old way we did things as we continued to add new features. We needed to get it out of the way now.
It hasn't been perfect, and both Sean and I have been busy with other things in life as well, so that's why it took a while to get these things done. Hopefully there will be less issues going forward.