Green ball indicating availability of Tahm's ult not functioning properly

Every game I've had with a Tahm Kench on my team have used their ult but the green indicator, next to their champion profile to the right of the screen right above the map, will not go down and display the remaining cooldown time of their ult. This is specific to having Tahm Kench on your team and I don't know if its a problem with other champions. I've also confirmed with the players playing Tahm Kench to actually know if their ult is on cooldown. The indicator says that their ult is up but the players I've chatted to say otherwise.