I am using firefox on the mac and just added the Toodledo add-on. I have successfully added tasks using the shortcut on my toolbar. However, the date when the task is due is not syncing with the toodledo site. I can see my task and what I have written, but the date never follows over. The date field is empty.
Not sure if this will help, but I remember seeing somewhere that the Firefox plugin on the Firefox addins site was outdated (I think it says it in the comments for the plugin) -- this affected Firefox for the PC, so could be a similar problem for the Mac too.