Ildar, we are unable to reproduce this issue with the following settings:
Versions tested: 2014 Q2 SP, 2014 Q3
Mask="", FormatString="n2", Culture="ru-RU"
Windows Region and Language format: Russiam
We clear the mask, after pressing 3, the input is "3,00" which is expected.
Please let us know if we have missed something.