I had the same problem. This is how I solved it.
I replaced the built-in terminal iTerm2, which also gave me some other nice features. To get a normal meta key, I did the following:
For the profile that I wanted to use, I checked "Alt send + Esc", which returned me a reasonable meta key that works in Emacs, Bash and others. However, I lost the backslash key. Thus, to return it and add the anchor in the profile that performs "Send text: \", and then anchored it to my backspace key combination (Shift-Alt-7, I'm Norwegian).
Now I have Mf, Mb in Emacs, M-. in Bash and I can send a backslash. I also have a Visor shell session that can be pushed down by pressing another key combination.
perbu
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