Google's new Pixel 2 and Pixel 2 XL have a special Active Edge Squeeze feature, but there are some occasions during normal operation where the phone is actually programmed to ignore the input that triggers the feature. The list is inconclusive and certainly not final, since Google could change it with an update at any time. For now, going into immersive mode, hiding the navigation bar, using the Google Camera app, or making a phone call will all temporarily disable the function. This is to prevent users squeezing the phone by mistake during an activity like making a phone call or watching a video, then having Google Assistant or whatever function they've assigned to the feature interrupt them.
Disabling the feature in immersive mode means that it won't work while the user is inside any app that uses immersive mode. Likewise, if a user has modifications or apps made to trigger immersive mode outside of its usual function period, which is inside select apps that call for it, Active Edge squeeze will not work while the mode is enabled. Likewise, pressing the home button while in a call and navigating around the phone will not restore the functionality; according to code found regarding the feature, the core activity that powers a phone call is one of the things that disables the feature, not the dialer or call screen. The same goes for hiding the navigation bar; whenever it's hidden, no matter what app you're in or how it became hidden, Active Edge Squeeze won't work until it's back up.
For the time being, nobody has stepped up and made a modification that will re-enable Active Edge Squeeze during Immersive Mode and other times it's disabled. Presumably, since the code that disables the feature has been found and isolated, all somebody would have to do is get root privileges and insert some contrary code or nullify the code at hand. Another potential approach could be to actually take the code out and repackage the resulting firmware in a custom ROM. In any case, for the time being, Pixel 2 and Pixel 2 XL owners should be cautioned that these circumstances will disable Active Edge Squeeze.