I have a map package and scene package which each include a layer provided via Koop. The Koop service is hosted in AWS behind a load balancer which provides TLS encryption. In one Android app only, ArcGIS Runtime SDK v100.15.6 makes a request for the layer, but silently fails to retrieve it. In a bare bones sample Android app, and in iOS, the Koop provided layers are properly retrieved. Unfortunately this Android app which has the issue is too large to simply compare with the sample app to determine what's different.
I used Wire Shark to inspect the traffic when the request is made by the failing Android app, and it appears that the certificate is being rejected, with "Certificate Unknown (46)" (screenshot attached). The cert is a standard AWS certificate, I've tried creating a new certificate, both a wild card and explicit domain certificate, with no change in any case. I've also verified with 3rd party tools that the TLS encryption is working and up to date.
This app makes other requests, without ArcGIS, to the same domain (which uses the same TLS certificate), with no issues.
Any guidance or insight into what could be causing this would be appreciated. I'm also happy to relay any information I can provide.
