This is a known problem and here are the instructions to fix it:
1. From the online help for Mobile Center 3.0, it says ''To work with iOS 12.2, download the support for iOS 12.2 content pack from the AppDelivery Marketplace.
2. Click on that link. This will take you here:
3. Download the proper file for your connector and/or server (Windows, Linux or Mac)
4. This file will be put on your connector:
3.00.00.0026-hotfix-Windows_connector_x64.zip (this is the Windows version, Linux and Mac will be slightly different)
5. Extract all the files from the zip file.
6. Run the following file:
connector_patcher-x64-3.00.00.0026-141.exe (Again, this is the Windows version)
7. Look in the files directory and copy the file listed below to your Mac machine:
8. On your Mac machine, extract all the files and put them in new directory.
9. Note that you need to resign the Agents provided in the content pack (located in the Agent folder), using the MC 3.1 Enabler. (https://marketplace.microfocus.com/api/download/193039?returnUrl=/appdelivery/content/mobile-center-310)
10. Download the Mobile Center 3.1 Enabler
11. Run the Mobile Center 3.1 Enabler and resign the Agent files located in the new directory you just created.
12. You should have these files:
13. Take these files and put them in the following directory:
C:Program FilesMobile Center ConnectorconnectorAgent (This is for Windows)
14. Rename the files removing the ''-Codesigned'' and replace the files currently there.
15. Remove the MC Runner, MC Agent and MC Launcher apps from your iOS device.
16. Unplug your iOS device from your connector, wait 5 seconds and reconnect your iOS device to your connector.