I found solution to the bug related to getblocktemplate mining method.
New version of wallet, with this bugfix and other upgrades, will be released in few days for Windows, OS X and Linux.
Will this be released soon?
Of course, 1.0.1 release is still being worked on, but since there are not many changes (you can check Github), it will be probably released after I get both Linux and OS X wallet tested.
I don't have any OS X machine, so testing it is hard for me. I already posted beta version of OS X wallet in this thread, but nobody reacted to it. If you have OS X machine and would like to help with testing, please PM me.