Campaign conversion total much higher than sum of conversions for each keyword in campaign.

Hi Piwikers,
I have a number of campaigns that are reporting no or very few conversions for keywords, but have significant conversions in the total for the campaign.

http://postimg.org/image/b2o8xs8c5/

It looks like this is happening when the users are coming from Baidu or 360 search engines whereas the problem doesn't happen for users coming from Google.

Any idea what might be causing this?