I have seen a few threads regarding the subject issue, and wanted to post a solution that I recently found.
Before:
After:
This was fixed for Android. When will IOS have BUG-000086811 fixed?
This is also fixed in iOS Collector recent release. There is no BUG associated with it.
Just to be clear, this is bug is associated with a hosted feature layer in ArcGIS Online or Portal?
“Collect New" order of Collector should match the layer order of webmap from either ArcGIS Online or Portal.
So my Layer list order on my feature layer is correct in my web map. It is correct in the legend of the feature layer in Portal 10.3.1. I know that these read a different part of the feature service json from ArcGIS Server. My Edit- Add Features list is still wrong in Portal 10.3.1 and in Collector 10.3.6 it is still wrong in Collect a New Feature for this new version 10.3.6. I have been waiting for this to be resolved, but it might have to wait till next year. I have seen that the "Types" section of the feature service json is not in the order created in ArcMap when publishing. This "types" section is the layer list that portal/collector reads when going to create new features. I have heard that 10.4 is fixing this issue in Q12016 from the source which is when publishing a feature service that this is put in the correct order like in ArcMap or the next update of Collector will read the other part of the feature service with the right layer order.
Thanks for your help!