Cannot "put" files using sftp

I’m using fly with a sqlite db. Once in a while I want to update it directly. I used to be able to simply sftp the db to the server, but this does not seems to work anymore. I’ve try with a simple txt file and that works, but for the DB (<200kb so quite small), it just seems to hang there:

» put test.txt /tmp/test.txt
10 bytes written
» put prisma/data.db /tmp/data.db

Any idea what this could be?