Hi!

Just as the player above said, it is not a bug. Both you and your opponent must use their mystery before a chase that can absorb chakra starts. The reasoning is that mysteries do not just happen instantaneously but it happens right after the current action or turn (with attention to Initiative and ninja positioning if multiple mysteries are cast). So if a chase that can absorb chakra starts, this can have the potential of stopping an opponent from using their mystery. This happens if the player's chakra is reduced below the amount of required chakra to use mystery.

~Jib