There’s definitely what I’d consider a bug in iOS that isn’t setting your default sort direction when entering the watchlist and other personal lists. That’ll be fixed in the next version.
On old web version it shows all TBA releases in the end of the list, which is kind of logical, but in iOS app it shows TBA releases in the beginning of the list. Can it also be fixed to show TBA in the end? Or am I getting something wrong?
Regarding my previous comment, as I dug a bit deeper, on old web version Lists previews are hardcoded to show only Ranked sorting (even though inside the list you have another default sorting). Workaround to this, specifically for me is to reset Ranked sorting and it will assign ranks according to your default sorting, thus on the Lists previews it will show items which correspond to your default sorting, downside is that you have to reset Ranked as you add new items to lists all the time.
If you have access, please try out beta version 3.2 (1003) and the sorting should be working as expected. If not, it should be available via the App Store in the next week or so.
For the positioning of TBA releases, without thinking too much about it personally I’d say they probably belong at the start of the descending list as they’d be in the future. Maybe it’s possible for something to have been released in the past without a release date in which case that probably needs to be a separate flag. This issue is probably worthy of its own feature request if it’s important to you.
For the sorting of previews issue, in general I would advise against trying to optimise what you see in the classic website and instead provide feedback on the new website if it’s not displaying as you expect as that will also then apply to the apps. If reseting the rank via the classic website works for you in the short term then that’s the best workaround available.