pg_probackup version: pg_probackup-11 2.4.10 (PostgreSQL 11.11)
os version: debian stable on db server and on backup server

I've set a remote backup system up according to the docs.
When on the backupserver i execute:
ssh postgres@dbserver.com
It connects perfectly.
So I've added a backup instance:

pg_probackup-11 add-instance -B /var/lib/pg-probackup-11/ --instance 'test' --remote-host=dbserver.com --remote-port=1024 --remote-user=postgres -D /var/lib/postgresql/11/main
INFO: Instance 'test' successfully inited

So far so good. It connected successfully over ssh. I've checked auth.log on the db server.
But know when I do a backup:

pgbackup@backup:~$ pg_probackup-11 backup -B /var/lib/pg-probackup-11/ -b full --instance 'test' --remote-host=dbserver.com --remote-port=1024 --remote-user=postgres -U backup -d backupdb
INFO: Backup start, pg_probackup version: 2.4.10, instance: test, backup ID: QRQ1QT, backup mode: FULL, wal mode: ARCHIVE, remote: true, compress-algorithm: none, compress-level: 1
ERROR: could not connect to database backupdb: could not connect to server: Connection timed out
Is the server running on host "dbserver.com" (123.123.123.123) and accepting
TCP/IP connections on port 5432?

I've checked out auth.log on the db server. It doesn't even try to connect over ssh. It seems like it tries to open directly an postgresql connection to remote-server?

I've also tried:

pgbackup@backup:~$ pg_probackup-11 backup -B /var/lib/pg-probackup-11/ -b full --instance 'test' --remote-host=dbserver.com --remote-port=1024 --remote-user=postgres --remote-proto=ssh -U backup -d backupdb -h localhost
INFO: Backup start, pg_probackup version: 2.4.10, instance: test, backup ID: QRQ1XU, backup mode: FULL, wal mode: ARCHIVE, remote: true, compress-algorithm: none, compress-level: 1
ERROR: could not connect to database backupdb: could not connect to server: Connection refused
Is the server running on host "localhost" (::1) and accepting
TCP/IP connections on port 5432?
could not connect to server: Connection refused
Is the server running on host "localhost" (127.0.0.1) and accepting
TCP/IP connections on port 5432?

WARNING: Backup QRQ1XU is running, setting its status to ERROR

And still. It doesn't even try to do a ssh connection (auth.log on the db server is just empty).

I've tried some more stuff, but it seems like I can't get it in any way to use the ssh connection.
--log-level-console=verbose
doesn't help at all. No extra output.
For me it looks like some kind of bug, but since it seems like everybody else got it working.... hmmm ?