This could be due to a few different reasons:

Language settings: The AOP30 may be set to display information in a language that it does not support or recognize. Make sure that the language settings on the AOP30 and the device it is communicating with are compatible.

Communication issues: There may be an issue with the communication between the AOP30 and the device it is connected to, which is causing the AOP30 to display incorrect or incomplete information. Check the wiring and configuration of the communication network to ensure that it is set up correctly.

Firmware issues: The firmware on the AOP30 may be outdated or corrupted, which could be causing it to display the question marks. Try updating the firmware or performing a factory reset to see if this resolves the issue.

Hardware issues: There may be a hardware issue with the AOP30 itself, such as a faulty display or connection. If none of the above solutions work, you may need to contact the manufacturer for further assistance or to have the device repaired or replaced.

I would recommend checking these potential causes in order to troubleshoot the issue with your AOP30.