This was an issue a few months ago, but I am sure it was fixed.

I did a few last night and weights came up as metric.

The workaround is to select 'Pickup Only', then reselect proper postage and it should then be metric. Are you 100% you have the Australian version, not the US one? Anything you do from the boards puts you on eBay.com, so it is easy at the moment to end up on the wrong site. Also try a full version update; that might help.