The next version will display information about the effect of preserving directory timestamps on background transfers:
Issue 2439 – Informing that when preserving directory timestamps is enabled, using multiple connections for transfer is not possible

Thanks a lot!

See https://winscp.net/eng/docs/ui_pref_background#fn1

Multiple connections are not used, ... when preserving timestamps of directories is enabled

Recently WinSCP stopped running multiple transfers for downloading a large number of files from a single server.
Settings | Transfer | Background | Background Transfers is set to 7
All the options on that dialog are ON, including 'Use multiple connections for a single transfer'.
Single transfers (no multiples) happen from several FTP servers.
Not sure if this is a bug, more likely it's some setting I'm missing.
It happened with a previous version of WinSCP v5x??, I upgraded to WinSCP 5.18.3 RC with the same problem. Windows 10 latest version.
I suspect it's a setting - but which one? What's changed? I've tried many combinations but can't get the long-standing multiple downloads working again. Any suggestions would be appreciated.
Log file attached of a short download session.
Thanks,