v8.1.21
I've got an Ignition Edge Gateway installed on a client and Perspective Workstation (PW) installed with a client configured to the main Ignition (Standard) Gateway, with fallback to local Edge project. I tried unplugging the ethernet from the client and it successfully fell back to local.
This particular client is connected to the main network via a radio link. When I disconnect the radio link, PW has the banner up top saying "No Gateway Connection" but there's no timer to fallback, and it doesn't ever revert to local fallback gateway.