Just and update:
After talking to support they suggested resetting the devices as they couldn't find the issue either. And that's what I did as I tried far to long to find the issue. There seemed no way around it and fiddling to find what the problem was, was going to take more time, then just starting from scratch and then utilizing my TitaniumBackup afterwards...
After resetting the update to 3.2.1 was no problem.
I also could get my boot.img for both a and b partitions.
Code:
python3 edl.py r boot_a boot.img --memory=ufs --loader=prog_firehose_life_ddr_patched.elf
python3 edl.py r boot_b boot.img --memory=ufs --loader=prog_firehose_life_ddr_patched.elf
Which one should one generally use for patching vai Magiks?