@Emil I tried removing the Chromecast device from the app and all associated actions and then add them back again, but that didn't work.
Then I tried to hard reset(by pressing the button between 10-15 seconds) the Hub to its original firmware and the Chromecast actions will work again.
But after updating to the current firmware v2.0.19 the issue came back again!

When I try to pause/play anything playing on the Chromecast via Hub 2.0, It won't work and the Hub would reboot!