Some of the texts are in the right order, but more and more the responses are showing up above the message. It's very frustrating and caused me to miss responses because they are integrated in the sent messages. What is more interesting that Apple watch shows the iMessages in the correct order but the iPhone does not. The issue is reported by many user once they upgrade to iOS 11.2. The issue is very annoying as it loses basic sequence of conversation, Message texts are misplaced just about every other time . And the issue is not very rare across different iPhones, it can be seen on multiple iPhone including iPhone 6s/7/8 plus.
So far there are no updates from Apple on this issue so it is suggested to always upgrade to latest iOS 11 published by Apple, as new it is possible that new releases have fix for out of order iMessage in iOS 11.
How to fix iPhone iMessage messagre out of order in iOS 11
Fix 1: Reset date/time in Setings
Even if you are sure that you are in correct time zone it is recommened for you to try below steps to fix the issue
1. Turn off ‘set automatically’ under date/time in settings.
2. Now change time to other value like one minute early
3. Now Turn on set automatically under date/Time in settings.
4. Restart iPhone
Now the iMessage messages should order them in proper way.