UEFN / Unreal Editor For Fortnite (App name: "Fortnite_Studio") has an error when launched with Legendary but works fine with Epic Games Launcher.

[cuhsy]

UEFN / Unreal Editor For Fortnite (App name: "Fortnite_Studio") has an error when launched with Legendary but works fine with Epic Games Launcher.

Platform

Operating system and version: Windows 11 Home 23H2
Legendary version (legendary -V): v.0.20.34

Expected Behavior

UEFN launches successfully

Current Behavior

An error that says "Invalid backend requested! Exiting." appears. (1st screenshot) Then, the initializing screen/launcher appears, but then it closes and nothing happens after, and no UEFN is anywhere to be found in the task manager.

F:\Epic>legendary launch Fortnite_Studio
[cli] INFO: Logging in...
[Core] INFO: Trying to re-use existing login session...
[cli] INFO: Checking for updates...
[Core] INFO: Getting authentication token...
[cli] INFO: Launching Fortnite_Studio...
(Then the problem appears)

Steps to Reproduce

1. Own the Fortnite DLC named "Unreal Editor For Fortnite"
2. Install and launch it

Additional information

It works perfectly fine on Epic Games launcher but not on Legendary, so it's not a problem with my computer. (I believe so)