Hey Lawrence,   What you've described is similar to something that we see with some frequency in the run-up to a new major version of iOS: that iOS no longer likes the code signature of your apps.  If you collect console logs off of a client manifesting the problem during the installation attempt (see: https://documentation.meraki.com/SM/Other_Topics/Finding_Console_Logs_for_iOS_Troubleshooting ) you should be able to see an error you can then either take to Apple or search for to get you moving in the right direction.       ... View more