As requested, I've just sent you an email.

Thanks for your report.

This bug has been added to the tracker:
https://winscp.net/tracker/1936

Can you send me an email, so I can send you back a development version of WinSCP for testing? Please include a link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.

I've got a PowerShell module which uses WinSCP (5.17.9). When I apply the DebugLogLevel to the session the value -1 which is supposed to represent 'Reduced' doesn't apply. The log level remains as 'Normal'. I can see in the session output within PowerShell that the value is assigned as -1, but it's as if it's being ignored. It works fine for Debug 1 and 2.

If I manually assign a value that clearly isn't available e.g. -2 then I get the following error:

Exception setting "DebugLogLevel": "Specified argument was out of the range of valid values.
Parameter name: Logging level has to be in range 0-2"

I can still assign the value as -1 without any issue. So I guess the error message just hasn't been updated. The GUI works fine.
Anyone else had any issues with log level for 'Reduced'?