In the new version of Windows Spotify app, there is a major playlist issue that makes playlists extremely broken if you care about organizing them. If you select two or more files and re-order them, it doesn't actually re-order those files and then permanently breaks that playlist so that it is no longer accurate on Spotify's server.
I've already ruined about a dozen carefully curated discography and other important playlists by not realizing this sooner. I'm hoping you read this and don't wreck all of your existing playlists until Spotify fixes this!
Once this breaks, you can never fix it by re-ordering the tracks, and the order will be displayed inconsistently across all your devices. It essentially mixes up the songs somehow, I don't understand how it's possible, but it is.
Here's a video explaining it with the broken Desktop app on the left and the web app on the right. The web app functions just like iOS, by the way, I just can't show that with a screen recording.. I did have all 3 open to check:
Note that I checked the Song Credits and even played the songs.. it's not a visual bug, the songs that are broken actually play.
I'm not sure of other implications (what happens if you select 3+ songs, or if this issue happens with single selection), but as of right now, I think I need to abandon the Windows app until this is fixed. I'm already noticing I ruined many carefully constructed playlists, I don't want to cause any more damage.
(Premium account, Windows 10, latest version of Desktop app, tested on three different computers)