Async Shell Command not advised
It appears that async-shell-command isn't appropriately advised. When running interactively, for instance, with M-& echo foo, the standard Emacs "Async shell command" style buffer name is used.
Hm, have you activated shell-command-x-mode? I use M-& all the time
Alternatively, I wonder if there's some path somewhere in async shell command that doesn't call the advised functions in this package. I'll have to take another look at the function. Are you using this package in conjunction with similar packages that may conflict?
I have enable shell-command-x-mode. I don't believe I'm using any similar/conflicting packages.