When I call DeviceId.getID in debug mode it gives me an ID that's different from when I call it in release mode. Hence, device ID from release mode and debug mode are different. This happens on android I don't know about iOS
I got this issue too, similar with your experience, I found DevicdId.getID changed while I packing a release package with difference keystore of debug mode.
Maybe the signature is the problem?
When I call DeviceId.getID in debug mode it gives me an ID that's different from when I call it in release mode. Hence, device ID from release mode and debug mode are different. This happens on android I don't know about iOS