Looks like I introduced an interesting bug with the last release of my rsync4j library, by adding support for additional arguments to be supplied to rsync:
It forced you to supply an additional argument and if you used an empty string, that would screw up your rsh argument, resulting in the current directory being used in the rsync process.
Anyhow, since I had to make a new release, I also updated all the Windows binaries. It now uses OpenSSH 7.7p1-1 and Cygwin binaries as of 2018-06-27 (NZ time).
The current version is now: 3.1.2-11