To mark pictures as burst in Apple Photos.app a random BurstUUID (same one for all bursts) is required.
By trying to set an UUID with zsh: exiftool -BurstUUID='A4862FFE-5491-4F15-9AC0-0881859A0802' sample.jpg
it returns
0 image files updated
1 image files unchanged
Does anyone know why that's the case? Would be very happy for getting an answer ;)