Not sure why the .3 update would have stopped you from duplexing. Hasn't impacted duplex printing to my printers.
To confirm, you are able to select the duplex setting via the Layout tab or via a HP finisher menu as you have done previously but the printer does not print on the second side.
If you haven't done so already, try removing the printer from Print & Scan and adding it again. I would also check the driver settings in Print & Scan > Options & Supplies > Driver to ensure that you have the Duplex setting enabled - assuming that such a setting exists.
If the above does not help then you could try a reset of the printing system. This will remove all printers and scanners from Print & Scan, but not the supporting drivers, so you will only have to add them to Print & Scan again.
I've already tried resetting the print system and that made no difference. I've checked print two-sided evefrywhere and I've tried printing with various applications so this isn't app specific.
At first I thought this was something due to an Adobe document I was printing but this wasn't the case.
Thanks anway. I've also posted my problem over on the HP forum and haven't had a response from there.
Final note: after finally talking with an HP support "supervisor" who decided that the printer was at fault, HP sent me a replacement. Then I had to reset the printing system and reinstall the printrer software using the HP downlaod. Apparently there are differences between what comes in softwware update and what HP sujpplies.