We apologize for the inconvenience. Based on feedback from some Russian-speaking users, we've found that when your Windows system language is set to Russian, you are unable to enter battle levels. We will try to resolve this issue as soon as possible, but we don't know how long it will take. Current Russian-speaking users who wish to play the game normally can consider changing their Windows system language to English and setting the in-game language to Russian. This will allow them to play the game normally.
We sincerely apologize again for any inconvenience this may cause!