Why does WinSCP see remote files as changed/updated when they aren't?

Question

Good day.

I'm using WinSCP to synchronise a folder on a remote server to a folder on my computer (my local folder becomes the copy). The folder contains lots of .TXT and .LOG files, and a few subfolders also containing the same filetypes. I use the Commands -> Static Custom Commands -> Keep local directory up to date feature to keep my local folder synchronised. This feature spawns a PowerShell script which checks the remote folder every 30 seconds. If there's any new/changed files, it downloads them to my local folder. This worked for months, but suddenly it's seeing many old files as 'changed' when they aren't. Every time WinSCP checks the remote folder it will detect 1200+ changed files when in reality only 3 or so have changed. It will download all of those 1200, then check remote folder again and detect the number of files as 'changed', downloading them all again. Note that the number of 'falsely changed' files can differ on every remote check, varying between ~900 and ~1300 files. The total number of files + folders in the remote directory is ~2470. This cycle of false-positive change detection continues endlessly, downloading thousands of files insteads of the 2 or 3 that it should.

I've tried re-installing the WinSCP, deleting the server bookmark and making a new one, and running WinSCP as admin. None of these work.

I'm connecting to a remote server via FTP protocol, without encryption.

--Update to Martin Prikryl--

Two sessions have been logged, download these logs here.

A few notes:

• I tried running this on a subfolder called 'archive-08-2020' to limit logsize, but I couldn't reproduce the problem. This subfolder did a full sync of it's ~800 files, but noticed no changed files after the first sync round. Hence the two WinSCP logs are from operations on my main, large folder. Sorry for this inconvenience.
• On both sessions, the logfiles have iterated over all files in the folder several times already while the PowerShell screen is still working on the first run of downloading all of them in order.
• The files in the remote folder start at chatlog_2020-09-01_0121.txt but the PowerShell window only starts at chatlog_2020-10-25_0334.txt each time, even on consecutive iterations within the same session. WinSCP session log also starts at chatlog_2020-09-01_0121.txt.
• The remote folder has 4 subfolders: archive-05-2020 through archive-08-2020. The archive-08-2020 files are logged in the WinSCP session log, but none of the other subfolders are.
• One example of a file that should not have updated but still did is chatlog_2020-11-30_2210.txt

Answer 1

It seems that the timezone offset autodetection fails with your particular FTP server for some reason. It may started failing with end of daylight saving time in October?

Try to disable the timezone offset autodetection at the Environment page of Advanced Site Settings dialog. Try setting it to 0:00.