Author of VICREO Listener here — sorry this sat unanswered so long.
What you're seeing is real, and it isn't a misconfiguration. On macOS the Listener sends keys through AppleScript's System Events, which hands the key to whatever application is frontmost — that's why it types into Notes correctly. OBS doesn't read hotkeys that way: it installs a listen-only event tap at the HID layer, the point where physical keyboards enter the window server, so its hotkeys keep working while you're in another app. A key synthesised through System Events never passes that layer, so OBS's hotkey engine never sees it. A physical press does enter there, which is why that works.
So granting OBS Input Monitoring won't fix this one. Grant it anyway — it's required for OBS hotkeys from a real keyboard while OBS is in the background — but it isn't the missing piece here.
Two things that do work:
1. obs-websocket, and that's what I'd recommend. It's built into OBS 28+ (Tools → WebSocket Server Settings), and the OBS Studio module in Companion drives scenes, recording and streaming over it, with state coming back to your buttons. For anything OBS can do itself it beats a keystroke on every platform.
2. If it has to be a keystroke: the Pro action "Send KeyPress To MacOS Process" with process name OBS. It brings OBS to the front and types into it, and OBS does convert key events it receives itself into hotkey presses. Needs Settings → Advanced → Hotkeys → Hotkey Focus Behavior set to "Never disable hotkeys", and it takes focus — so test it on that machine before relying on it.
Worth knowing: Windows behaves differently, because keys are injected into the same input stream OBS watches there. A setup proven on Windows can move to a Mac and silently do nothing, which I suspect is how most people end up in this thread.
Full write-up, including which permission buys you what:
https://www.vicreo-listener.com/control/obs
