Cannot set modifier+key shortcut

When I try to set a recording shortcut with modifier keys + another key (e.g. cmd + \) it immediately sets the shortcut to the first key press (e.g. cmd) and ignores the second key press. If I use multiple modifier keys (e.g. cmd + option + \) it only sets the cmd + option part. This makes it very difficult to set a usable shortcut. I’m guessing this changed recently as I was able to set multi-key shortcuts previously.