This morning I just did a fresh upgrade to 5.13.5 (build 8967).
I don't know if I had it before, but I just noticed this behaviour:
I have a directory on the server "/ftp/sales0530/2018-12-06/" with a lot of reports in it (1023 files -- list in attachment via "find . -type f").
I was looking for a matching report with the names "KD269000QE" and "KD26900774".
I could find the "QE" fast enough, but the "774" report I couldn't find. But I knew it should be there... So I went to the server directly and did a listing to see...
That's how I noticed this problem.
If you look at the list I copied via SHIFT-CTRL-C, you'll see that the sorting is all wrong. This is actually how I see it here. I refreshed a few times, sorted descending and ascending. Changed sorting to date sorting and back to name sorting, but it doesn't work. Meaning that the sorting is still wrong.
When I load up the list in Notepad++ and sort it via the TextFX plugin, the sorting is done properly. But it's not done correctly in WinSCP somehow?
I hope you can look at this soon-ish because this is really annoying (I can't understand why this would be wrong. The only thing I notice is that the wrongly sorted names are all numbers, but this shouldn't matter as the filenames shouldn't be "naturally" sorted anyhow?