Hi Ted,
update on https issues you found before: We got to the bottom of the https issue you reported and will address it in our next release of the app (planned for around March 3). For completeness, the issue was that you first published your Survey as http, and then switched the security to https only. This caused the app to break because the Survey was already on http but the ArcGIS Online organization would no longer support http calls. In the next update of the app, a fix has been added so the security settings of your ArcGIS organization are double-checked before submit. Thanks for reporting the problem.
as far as the 400 error, can you confirm if you are using images in your Survey? These images may be causing the problem. It has been reported that this error pops when you are submitting a Survey with images over a cellular network. If submitting over a reliable WIFI, the submit happens correctly. We are also working on this so we can provide a fix in the next update immediately after March 3.
Ismael
