STM32H747I-DISCO Dual-Core Communication in OpenAMP example

[WHMJJ]

I am currently using the STM32H747I-DISCO board and trying to implement Dual-Core communication using OpenAMP. I am encountering communication failure when using the provided sample code, and I am unsure about the root cause of the configuration issue. Thank you for your assistance!
Configuration Method
M7 Core: Flashed with the src/main.c from the OpenAMP sample [1].
M4 Core: Flashed with remote/src/main.c (my understanding is this is for the M4).
Both cores use the same overlay [1], detailed below.
Programs were built separately and then flashed to the respective cores using west flash.
M7 Flash Procedure
Path: \zephyrproject\zephyr\samples\subsys\ipc\openamp

M7 Build:

west build -p -b stm32h747i_disco/stm32h747xx/m7 -- "-DDTC_OVERLAY_FILE=boards/stm32h747i_disco_stm32h747xx_m7.overlay"
west flash
M4 Flashing Procedure
Path: \zephyrproject\zephyr\samples\subsys\ipc\openamp\remote

M4 Build:

west build -p -b stm32h747i_disco/stm32h747xx/m4 -- "-DDTC_OVERLAY_FILE=boards/stm32h747i_disco_stm32h747xx_m4.overlay"
west flash
Current Result
On the M7 side, all other initialization steps report no errors. However, execution halts at the line k_sem_take(&data_sem, K_FOREVER); because it does not receive the notification from the M4 (the platform_ipm_callback is not triggered). The M7 is stuck waiting for the M4's message.
Question
I haven't been able to pinpoint the configuration setting that is causing the issue. Since the M4 cannot use printk, it is difficult to confirm its status. I would like to ask the experts if there are any effective methods to debug and resolve this? Thank you!
Sample URL [1]
https://github.com/.../main/samples/subsys/ipc/openamp
Overlay Code

DTS
/ {
chosen {
/*
* shared memory reserved for the inter-processor communication
*/
zephyr,ipc_shm = &sram4; // sram4 domainD3 shared memory
zephyr,ipc = &mailbox;
};
};

&mailbox {
status = "okay";
};