Thank you for your post. Diagnostic logging from RoonServer shows the connection to the iOS device terminating around the time of your screenshot. There’s no known crash with iOS on the current Roon build, so we’ll need a few more pieces of information to assist here:
Please update your RoonServer to the current production build to ensure parity with your iOS remotes on 1516.
Diagnostics indicate that the Nucleus+ is still running build 1510. This might not cause the crash, but symptoms may differ significantly on the current build.
Have you reinstalled Roon on the affected iOS devices at all?
Please also provide a set of manual logs from the iOS device(s) - either device will work.
First toggle “Save logs to Files on next startup” from your iOS Settings for the Roon App.
Reproduce the issue.
Access your Files App on the phone and upload the log file.