Kill shot is now on the GCD so that macro wont work now. You also dont need /cast !auto shot as its completely unlinked from other shots now, its been this way since WotLK.

Just FYI, that macro would be a huge dps loss, as it would try to cast explosive shot when its on cooldown all the time. That castrandom line will hit explosive shot about 50% of the time, as it has a long-ish cooldown you'll be losing dps while it tries to do this.

If you just want that macro to start working again, take out the kill shot, or add kill shot it into your castrandom line.