I have attached a small datapack made for testing this along with screenshots of me generating test_room using its jigsaw block 2 separate times and getting different results but in both cases the generated rooms jigsaw is misaligned.
I have had this same issue, it seems to generate the structure with the jigsaws being misaligned by a block, sometimes the structure isn't rotated properly to line up the jigsaw too. But I'm not sure if I'm just doing it wrong or if its actually a bug.
Adrien Anderson
I have attached a small datapack made for testing this along with screenshots of me generating test_room using its jigsaw block 2 separate times and getting different results but in both cases the generated rooms jigsaw is misaligned.