In the announcement of the upcoming Thunderstorm event, we revealed some details about pre-battle screen improvements and changes to player movement permissions. However, during testing, we encountered a technical issue which requires more time to completely resolve than is left before the start of the event. As a result, we have decided not to risk the event’s stability by implementing these planned changes. Therefore, the mechanics of the pre-battle screen in Thunderstorm, including player movement permissions, will remain the same. We appreciate your understanding and wish you good luck on the battlefield!
Source: EU Portal