Arcane Missiles keeps canceling byself

[Destruktio-stormreaver]

I’ve no idea about the trigger, sometimes it just stops the channel after 1-2 missiles

[Coolgroove-defias-brotherhood (Coolgroove)]

• Check if you’re using a macro for AM, maybe something broke in it or there is more than one spell in the macro and they conflict (mod and nomod for ex.)
• Check if some addon or another bar uses same keybind as your AM.
• Check if you’re moving somehow while channeling it. Turning camera/character with mouse only is fine. Turning with keyboard or moving even a little bit is not.
• If you’re using Slipstream - there is a bug. It can randomly stop working. Best workaround is to stop for a millisecond before AM, then start to run again and press AM.
• If you try to start AM while on a mount, look where you stand, sometimes you can fall a bit and it’ll cancel cast. Like in a water on a strider or on top of a narrow edge.
• Sometimes knockback abilities don’t knockback (because of your positioning) but still interrupt cast.
• Bad internet connection with a lot of packet loss. I once played on a bad data connection and had a lot of weird stuff with character controls.

Maybe clear cache folder in your WoW folder, and also try Scan and Repair in Options of BNet launcher.

You could also try to disable all action bar & menus addon, like Bartender, OPie, etc, and play for some time without any of them.

Can’t think of anything else that might cause this.