I encountered the same issue with my iPad mini -- namely, when connecting to the front panel USB 3.0 port it receives only the base 500mA of current, but does not receive the additional 1000mA of "Extra Operating Current" that is necessary for charging.
After a little bit of searching I found a solution by RehabMan
described here. As a result, I've modified the USB SSDT with custom Power Properties taken from an iMac17,1 (because those values were readily available).
My iPad mini now charges properly from the front panel, but it receives 1600mA of Extra Operating Current.
Not sure if this is too high so I would certainly like to update the SSDT with USB Power Properties from Mac mini 8,1 and iMac19,1 if someone can provide their DSDT.aml file.
Meanwhile, please test the new SSDT as follows:
- Mount EFI partition of your Mojave SSD
- Move out or delete the current SSDT-UIAC-DESIGNARE-Z390-V6.aml from CLOVER/ACPI/patched folder
- Copy the new SSDT-UIAC-DESIGNARE-Z390-V7.aml in its place
- Copy SSDT-EC.aml to the same folder
- Reboot
- Login and attach your iPad directly to a front panel USB port (no hub)
- Does it charge?