Unable to alter values for any combobox when machine type is PowerPC64

**Describe the issue**
When I create a new virtual machine for PPC64, I cannot change any combobox value afterwards at any location of the settings dialog window.
I tried the comboboxes for System -> Architecture, System -> System, System -> CPU, Input -> USB Support, Sharing -> Directory Share Mode, Display -> Emulated Display Card, ... and basically all the other combobxes, too. Changing values for textboxes does work

I have added a quick time video to demonstrate my problem:
https://github.com/utmapp/UTM/assets/14310159/17cb0c98-af41-47ac-84f8-e471c4707c6a

I am able to edit values of processor, architecture etc. for aarch64 virtual machines and x86_64 virtual machines - this issue appears only for PPC64 and maybe other architectures which I did not test yet.

**Configuration**
* UTM Version: 4.3.5
* macOS Version: 13.5.2
* Mac Chip (Intel, M1, ...): M2 Max

**Crash log**
No crash and no crash log

**Debug log**
There is no debug log for the VM because I did not boot it up. The issue however is not related to the execution of QEMU but the GUI of UTM as I can neither use mouse nor keyboard to select any value of comboboxes.

**Upload VM**
[config.plist.zip](https://github.com/utmapp/UTM/files/12727524/config.plist.zip)