Could you try the new v6.0 M1 release here:
http://www.displaylink.com/support/downloads.php
This does have some fixes for the timing on HDMI at some resolutions, but it's 50/50 it will fix this. If it doesn't, then let me know and I'll raise a bug with the information you posted.
It would also be good to know if it is just this monitor that doesn't work at these resolutions, or does it happen on all monitors?
Thanks
Wim