Scoreboard doesn't always update Unsealed Spellbook changes

I played a game last night against someone using Unsealed Spellbook. According to the scoreboard, they currently had Flash and Teleport. After the next teamfight, we got a global message that they changed from Ignite to Exhaust. I checked the scoreboard, and it was still showing up as Flash and Teleport. My teammates saw the same thing I did and said so via discord. There were no other messages that we had missed. After 10-15 seconds, the scoreboard updated to show Exhaust.

At one point, the enemy top laner had changed to ignite with no global message and no updated scoreboard. That seems pretty gamebreaking if they can switch to ignite without the other team's knowledge.