"Keeping remote directory up to date ..." doesn't work when

Version: 5.1.2 (Build 2816)
OS: Windows 7 64-bit
Type: FTP
Interface: Commander

I'm trying to use the option "Keeping remote directory up to date..." so I click it's icon and a window pops up named "Keep remote directory up to date"

I click "Start".

Whenever I change a file, 100 % of the times changes get detected and the log says:
16:04:35 Change in 'K:\web\test' detected.

However, only roughly 30 % of the time,
the file gets uploaded.

Any idea why this is?
As long as it doesn't get uploaded 100 % of the time, I can never be sure whether they are in sync or not so this is a big problem :(

Can you see timestamps with seconds precision in remote file panel?

No, it's only hours and minutes in the remote file panel.

Seppe wrote:

No, it's only hours and minutes in the remote file panel.

See "Timestamp precision" on
https://winscp.net/eng/docs/timestamp