Many thanks for the helpful answer, myokaski!
I trained my MX3 remote to use the KEY_POWER code from rc6_mce. Now I can wake the Orange Pi PC up successfully.
Hopefully it would be easier to change CONFIG_CIR_WAKE_CODE in the future, as then one can be much more flexible with the choice of remote control.
Sorry for bumping up such an old thread.
I remember that about 5 years ago, waking up by IR remote control worked on Orange Pi PC running OpenELEC.
jernej, is it possible to achieve this nowadays with LibreELEC?
Many thanks @myokask, the latest nightly versions for both LE 12 and 13 seem to work properly so far! 
myokaski, thank you for sharing your experience, and sorry for the late response!
First, the issue is still there for the Orange Pi PC with the latest stable image (LibreELEC-H3.arm-12.0.1-orangepi-pc.img.gz).
I managed to flash the image for plus2e (LibreELEC-H3.arm-12.0.1-orangepi-plus2e.img.gz) and now the Orange Pi PC does boot successfully.
Nevertheless, Ethernet is not working, but I suppose this is to be expected due to the different SBC model. This is the relevant log entry:
[ 1.567211] dwmac-sun8i 1c30000.ethernet: Error: Failed to register MDIO bus for child /soc/ethernet@1c30000/mdio-mux/mdio@2
myokaski, would you please kindly share the steps you took for building a new working image for the Orange Pi PC?
jernej, how can the fix mentioned here be applied to the builds regarding Orange Pi PC?
Thanks!
jernej, is there any further information which would be useful for debugging this issue?
I confirm that with any of the following images, the Orange Pi PC does NOT boot:
1. current stable image LibreELEC-H3.arm-12.0.0-orangepi-pc.img.gz
2. current nightly for 12.0 LibreELEC-H3.arm-12.0-nightly-20240605-61123a8-orangepi-pc.img.gz
3. current nightly for 13.0 LibreELEC-H3.arm-13.0-nightly-20240606-58f0779-orangepi-pc.img.gz
Here is the serial console output for 2:
U-Boot SPL 2024.01 (Jun 05 2024 - 13:19:28 +0000)
DRAM: 1024 MiB
Trying to boot from MMC1
U-Boot 2024.01 (Jun 05 2024 - 13:19:28 +0000) Allwinner Technology
CPU: Allwinner H3 (SUN8I 1680)
Model: Xunlong Orange Pi PC
DRAM: 1 GiB
Core: 58 devices, 17 uclasses, devicetree: separate
WDT: Not starting watchdog@1c20ca0
MMC: mmc@1c0f000: 0
Loading Environment from FAT... Unable to read "uboot.env" from mmc0:1...
In: serial@1c28000
Out: serial@1c28000
Err: serial@1c28000
Net: No ethernet found.
Hit any key to stop autoboot: 0
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
Found /extlinux/extlinux.conf
Retrieving file: /extlinux/extlinux.conf
1: LibreELEC
Retrieving file: /KERNEL
append: boot=UUID=0506-0815 disk=UUID=c7985365-59e0-4fa8-bc24-81ba168d0d6d quiet console=ttyS0,115200 console=tty1
Retrieving file: /sun8i-h3-orangepi-pc.dtb
Kernel image @ 0x42000000 [ 0x000000 - 0x9cfe48 ]
## Flattened Device Tree blob at 43000000
Booting using the fdt blob at 0x43000000
Working FDT set to 43000000
Loading Device Tree to 49ff4000, end 49fff32e ... OK
Working FDT set to 49ff4000
Starting kernel ...And for 3:
U-Boot SPL 2024.04 (Jun 06 2024 - 10:12:07 +0000)
DRAM: 1024 MiB
Trying to boot from MMC1
U-Boot 2024.04 (Jun 06 2024 - 10:12:07 +0000) Allwinner Technology
CPU: Allwinner H3 (SUN8I 1680)
Model: Xunlong Orange Pi PC
DRAM: 1 GiB
Core: 58 devices, 17 uclasses, devicetree: separate
WDT: Not starting watchdog@1c20ca0
MMC: mmc@1c0f000: 0
Loading Environment from FAT... Unable to read "uboot.env" from mmc0:1...
In: serial@1c28000
Out: serial@1c28000
Err: serial@1c28000
Net: No ethernet found.
Hit any key to stop autoboot: 0
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
Found /extlinux/extlinux.conf
Retrieving file: /extlinux/extlinux.conf
1: LibreELEC
Retrieving file: /KERNEL
append: boot=UUID=0606-5509 disk=UUID=7dd3a53b-8a56-4bed-8e37-d60a6fadd293 quiet console=ttyS0,115200 console=tty1
Retrieving file: /sun8i-h3-orangepi-pc.dtb
Kernel image @ 0x42000000 [ 0x000000 - 0x9fdf58 ]
## Flattened Device Tree blob at 43000000
Booting using the fdt blob at 0x43000000
Working FDT set to 43000000
Loading Device Tree to 49ff4000, end 49fff32e ... OK
Working FDT set to 49ff4000
Starting kernel ...