Hey

It's not a bug.
It's connection and action. Players with prompt skills can either choose to wait till it's exactly at their standard so there's little time for the other player to react. It's a strategy, however, in return, you're allowing standards to go through to hide mystery intention.
If the opposing player reads his/her intention, you may time an interrupt to counteract it. However, it's a chance due to the player having a prompt skill.

If you have any questions, feel free to message me.