Please add me to the list of complaints as well. I have more than 1500 contacts, so sorting them in groups is extremely important. Just in case one day Apple will really solve this, here is a summary of bugs and complaints:
1. Bugs in iOS 9
- I updated my iPhone 6 to iOS 9, after that the contact groups are not sorted in alphabetic or any other order, just arbitrarily; but it is still possible to select one or more groups both in the contacts app and in the phone application, and contacts are shown correctly
- I updated my iPhone 4S to iOS 9, it showed the same behavior as above with the groups ordered in the same chaotic way as on my iPhone 6; because of that I decided to delete all contacts and to newly sync them with iCloud - with the effect that the contact app no longer shows any groups (only all contacts), but the phone app still shows groups in the same "unordered" sequence as before; in the phone app it is still possible to select one or more groups
2. Annoying features before iOS 9
- in the address book app on a Mac you select a group and you see all contacts of that group, until iOS 6 this was all the same on iOS: contacts>group and you see the contacts of that one group; since iOS7 this is gone: you can select more than one group with the effect that you need more clicks if you want to change from one group to another
- the above has also the "nice" effect that it is quite hard to define to which group a newly added contact will belong if you add it on your iPhone, for sure you can't see it e.g in the "edit contact" window and hence you can't change the group of a contact on the iPhone
- on Android phones you can simply select which way you want it: the pre-iOS7 way (just one group can be selected) or the other way (multiple group selection), I wish I would have that choice as well
- before syncing via iCloud was introduced and contacts were synced via iTunes one could select which contact groups shall be synced and which not synced, now it is "all or nothing" which again is not very helpful for people having more than 1000 contacts like me (a part of them are not really needed on the phone but I don't want to have two applications with addresses on my Mac: one for "phone contacts" and one for "not phone contacts"
All that shows that contact groups are not really in the focus of iOS developers. Probably not so many people are using them and that makes them "less important". So let's hope that at least the iOS 9 bug will be fixed soon.