Ok, I may have something useful here. I was working with a file that I have, and I created a list by pasting in some text. Each line became, as usual, one item. I then proceeded to add sub-items, etc. When I looked at this list in the Android client, the last two items had switched positions.
So I edited them in the web client, and checked how they synced and the changes were synced but they remained out of order. Ok. So I made a complete copy of the file. In the new file, the items were in the correct order on the Android client.
Next, I tried syncing that same problematic file with another Android device and wala! the items remained out of order.
So what do we learn here? Something about that particular list is consistently not getting synced with the correct order. I edited out the stuff in there that I did not care to share so that I could make the file available to you for troubleshooting. https://dynalist.io/d/UGyxNgIRIquxPdNBsEHOBZip
Steps to reproduce (apparently consistently):
1) Look at the file in a web client. There are two that are labeled "out of order 1" and "out of order 2". On the web client, you will notice that they are 1 then 2.
2) Look at the file using the Android client. Items 1 and 2 should be switched positions.
Tagging you @Erica and @Shida (I know you guys have a lot to do so just making sure this answer floats up on the radar that we may now have reproducible steps with this example file).