Remote to Local: Connection unexpectedly closed

I have several profiles to copy files from the phone to my PC and those work just fine. However I also added a profile to copy some files from the remote server to the phone and this one keeps failing with a 'connection unexpectedly closed' error.

I noticed that syncopoli did not like trying to set the modification times on the phone so I removed the '-t' option and any other option that looked like it could be causing trouble.

Also, although I get this connection error, syncopoli successfully removes local files that are not on the remote end (see 551981.gpx in the log). This proves the local folder path is correct and that Syncopoli has the permissions needed to write to it.

I enabled verbose traces but despite that I could not figure out the reason for the error. On the server I have Debian's rsync 3.1.2-2.1 and openssh-server 1:7.6p1-2 packages.

Here's the syncopoli log:

Thu Jan 04 11:56:58 GMT+01:00 2018

opening connection using: /data/user/0/org.amoradi.syncopoli/files/ssh -y -p 122 -i
/sdcard/Android/syncopoli.dropbear -l syncuser myserver.eu.org rsync --server --sender
-vvvre.iLfx . phone/Download/PCShare/  (15 args)
/data/user/0/org.amoradi.syncopoli/files/ssh:
Host 'myserver.eu.org' key accepted unconditionally.
(ecdsa-sha2-nistp256 fingerprint md5 xx:xx:xx:...)

receiving incremental file list
server_sender starting pid=26939
[sender] make_file(.,*,0)
[sender] pushing local filters for /data/phone/Download/PCShare/
[sender] make_file(bookmarks.html,*,2)
send_file_list done
send_files starting
recv_file_name(.)
recv_file_name(bookmarks.html)
received 2 names
recv_file_list done
get_local_name count=2 /sdcard/Download/PCShare/
generator starting pid=31143
delta-transmission enabled
recv_files(2) starting
recv_generator(.,0)
delete_in_dir(.)
[generator] pushing local filters for /sdcard/Download/PCShare/
[generator] make_file(551981.gpx,*,2)
delete_item(551981.gpx) mode=100660 flags=2
deleting 551981.gpx
recv_generator(.,1)
recv_generator(bookmarks.html,2)
generate_files phase=1
send_files(0, phone/Download/PCShare/.)
send_files(2, phone/Download/PCShare/bookmarks.html)
send_files mapped phone/Download/PCShare/bookmarks.html of size 50141
calling match_sums phone/Download/PCShare/bookmarks.html
sending file_sum
false_alarms=0 hash_hits=0 matches=0
sender finished phone/Download/PCShare/bookmarks.html
recv_files(.)
recv_files(bookmarks.html)
rsync: connection unexpectedly closed (307 bytes received so far) [generator]
rsync error: error in rsync protocol data stream (code 12) at
/home/vagrant/build/org.amoradi.syncopoli/app/src/main/jni/android_external_rsync/io.c(226)
[generator=3.1.1]
[generator] _exit_cleanup(code=12,
file=/home/vagrant/build/org.amoradi.syncopoli/app/src/main/jni/android_external_rsync/io.c,
line=226): about to call exit(12)

Sync FAILED (error code 12).