About the ammo being reloaded when charging the Rampage or Sentinel.

When I watch other players, I see that charging the Rampage or Sentinel reloads the ammo. However, on my account, the ammo doesn’t get reloaded. Is this a bug? I tried uninstalling and reinstalling the game, but it didn’t solve the problem. I also tried both keyboard and controller, but it still didn’t work. I tested it not only with one character, but also with other classes and characters, but it didn’t fix the issue.