There was / is also a problem some users have experienced: After downloading the latest version of SmartPlaylist (v5.9) SmartPlaylist crashes when opened. The same problem exists also with other apps. The reason for this seems to be corrupted files from the AppStore.
I have submitted a small update (v5.9.1) to Apple more than 10 days ago (fixing sorting after fusion / mix), but it has not yet been published by Apple. They seem to be really busy ...
UPDATE: OK, v5.9.1 has just been published in the App Store. I hope everyone gets a good copy this time.