Yes I am using a custom carrier board and Xavier NX SOM which is in stock condition. I am using jetpack 34.1 without any modifications.
Also, I went through Xavier flashing hangs at tegrarcm_v2 –isapplet with JetPack_5.0_DP - #33 by user100090.
After commenting out eeprom flags from the below files,
bootloader/tegra194-mb1-bct-misc-flash.cfg
bootloader/tegra194-mb1-bct-misc-l4t.cfg
bootloader/t186ref/BCT/tegra194-mb1-bct-misc-flash.cfg
bootloader/t186ref/BCT/tegra194-mb1-bct-misc-l4t.cfg
I was able to flash the board successfully. I think it is a temporary solution and waiting for NVIDIA to look into it and fix it.