STM32U585 - can't get SBSFU-example to work

Hi, I'm trying to adapt the SBSFU-Cube repository example for the B-U585I-IOT02A (STM32CubeU5\Projects\B-U585I-IOT02A\Applications\SBSFU, repository V1.7.0) to a custom PCB with STM32U585CITx. Since I don't have access to UART1 I changed it in com.h (both headers) and low_level_com.c to UART2. Also I'm using a J-Link, so I changed the connection configurations in the scripts accordingly. Since I don't have access to the BOOT0-pin I set the option bytes nSWBOOT0=0 and nBOOT0=1. Building the FW and running the scripts works flawless, also an investigation with STM32CubeProgrammer shows, that the binaries (Appli, Boot and Loader) are correct and at the flash-addresses where they are supposed to be. But when I reset the MCU after running SBSFU_UPDATE.sh there is absolute radio silence. Nothing shows on the Tera Term-terminal and also adding logs for Segger RTT viewer doesn't change anything, there's no feedback at all. I re-checked the option bytes, boot addresses, compared the flash content to the bin-files, checked the UART, everything seems correct. Tamper detection is deactivated as described in the example's README. I ran out of ideas how to debug the issue. I also tried it with the TFM_SBSFU example, it showed the same results. Is there anything not compatible regarding flash memory mapping between the U585I-IOT02A and the STM32U585CITx? Is there another file that needs to be adjustet for the use of UART2? Thanks in advance