Thanks for your report.
I will take a look at this issue.
To Replicate:
1. Open WinSCP preferences
2. (See attached image) Check Logging > Show log window > Display complete session
3. Configure a profile with user account for an SCP connection
4. Attempt to connect in with the user account
5. Authentication fails once (may need to force this to occur perhaps type wrong password)
6. Stop trying to connect
7. Re-open WinSCP preferences
8. Bug: The logging has been disabled
9. Bug: While connecting, the connection failed, but I cannot select or resize or scroll the logging window! It is useless to me.
Information:
Windows 7
WinSCP 5.7.6 (Build 5874)