I am finding a bug when I run many files at the same time. I think the error is because of this
write-protected regular file 'flow_registration/.git/objects/pack/pack-e3365ed17c5b56546a94b24b570cfb7232199589.pack'
I have managed to work around by re-cloning flow_reg. When I delete flow_reg it asks to delete some protected files. I guess this is causing the issue. I found this issue on the beta branch