FTPSync is not downloading new version on open

[NBostaph]

FTPSync is setup and connects correctly to our FTP server, per these settings:

"default": {
...
"upload_on_save": true, // set false if you do not want to upload on save!
"passive": true,
"download_on_open": true,
"overwrite_newer_prevention": true,
...
}

When I change files and save them they are uploaded correctly and without issue. However, I've noticed that when I open them, even though download_on_open is set to true, the file is never downloaded even if the copy on the server is newer.

For example, I just changed ztest.cfm in Notepad and uploaded a copy with Filezilla, so the server version is different than the version in my local working directly. I then went to Sublime text and double clicked the file. The console shows (with sensitive data obfuscated):

FTPSync > Checking {ztest.cfm} if up-to-date
FTPSync > Loading config: cache hit (key: G:\Misc\Work and Timesheets\PMI - ProjectManagement Dev\temp\ztest.cfm)
FTPSync [default] > Connected to: 172.24.16.162:21 (timeout: 30) (key: *************************)
FTPSync [default] > Logged in as: ******* (using password: YES)
FTPSync > Closing connection
FTPSync > No version of {ztest.cfm} found on any server

And the version that opens in Sublime Text is the old version. So for now our workflow is to download each file via Filezilla before opening with Sublime Text, which is a bit of a pain.

Is this a bug in FTPSync, or do we have an incorrect setting somewhere?