Hi @scarletlee ,
Thanks for your information.
Today, I also test it on my SLN-VIZN-IOT board with the SDK code:
SDK_2.8.1_SLN-VIZNAS-IOT\boards\sln_viznas_iot\sln_boot_apps
SDK_2.8.1_SLN-VIZNAS-IOT\boards\sln_viznas_iot\sln_vision_apps\elock_oobe
My MCUXpresso IDE version is totally the same as you.
My Segger Driver version is: V7.50.
This is my test result:


Please also download the bootloader and bootstrap, and disable the verification:



You can see, I can enter the debug mode.
BTW, do you have the segger JLINK? I am using the Segger JLINK plus.
You also can try my Jlink driver version.
Best Regards,
Kerry