Certain Tmux Meta (Alt) key bindings don't work

• I am on the latest Hyper.app version
• I have searched the issues of this repo and believe that this is not a duplicate

• OS version and name: macOS 10.11.6
• Hyper.app version: 1.0.1
• Link of a Gist with the contents of your .hyper.js: https://gist.github.com/flybayer/422d38acfcde635a6d333a7f66179e04
• Relevent information from devtools: N/A
• The issue is reproducible in vanilla Hyper.app: Yes, but only when setting modifierKeys: {altIsMeta: true} since my tmux config depends on that

Issue

I have the following in my .tmux.conf:

bind -n M-i next-window
bind -n M-u previous-window
bind -n M-y last-window

When I have two windows open, Alt-y works to toggle the windows, but neither Alt-i or Alt-u do anything. No response, no errors. These key bindings work fine in other terminals, just not in Hyper.

Any ideas?

P.S. This has been broken for a long time. I'm not sure if it ever worked.

Reproduce the issue in vanilla Hyper.app using the linked .hyper.js settings, modifierKeys: {altIsMeta: true}, and the listed .tmux.conf bindings. Start by tracing Hyper's keyboard handling for Alt-i, Alt-u, and Alt-y; done means all three bindings work reliably with tmux on macOS. No source file or test is named, and the issue has had no recent response.