What date format are you using as defined in Setup > General > Time & Place > Business Zones ?
You genius you... Thanks. I updated it to m/d/yyyy, and it now works as I want.
Glad to be of service! It did ring a bell with me and I did remember the workaround from the Advanced Engineers at SW WHD support. I think it it a bit of off the shelf code integrated into the application which is now very outdated.