Clearly, you have an issue with iOS on your phone.
You may have some malware on the phone so maybe, doing a factory reset on the phone is needed?
Or, it may be that Plexamp did not install 100% correctly on the phone. Try uninstalling Plexamp, power off the phone and then power it on again, then reinstall Plexamp.
Your Plexamp logs do not show anything alarming at all. Plexamp seems to be functioning properly from what I see in the logs. There are some warnings and the odd error, but nothing that screams serious issue!
