Since upgrading to 2.11, the calendars I set up previously are not selectable in tasks, when I either create a new task, or edit an existing one.
If creating a new one, it comes up with the 4 calendars I've created but when I deselect some of them, the deselection does not work.

When editing, whichever calendar the task had before, cannot now be changed.

For now as a workaround I've gone back to 2.10, though I MUCH prefer the preferences/options interface in 2.11, as well as having the menu bar icon.

I'm using Rainlendar Lite under Mac OS X 10.6.8 (Snow Leopard)

Thanks for your help!

The calendar selection doesn't work in Mac if the "Allow multiple calendars" is enabled. I'll try to fix it as soon as possible.

Thanks for letting me know so promptly - all the best for 2013.