Hello,
just started to test remote capabilities and I get :
/pg_probackup/pg_probackup add-instance -B /usr/local/var/lib/pgsql/mypgprobacks --remote-proto=ssh --remote-host=192.168.1.109 --remote-port=5432 --remote-path=/var/lib/postgresql/pg_probackup -D /var/lib/postgresql/datatest --instance testdblin
ERROR: src/utils/file.c:529: proceeds 0 bytes instead of 8

the catalog host is FreeBSD and the remote is linux. Could that pose a problem?