Existing Legendary credentials not detected / Epic auth via Edge fails to complete

[inlinealex]

Description:
Unifideck does not detect existing Legendary credentials and the Epic authentication via Edge fails to hand off properly regardless of OS.
Steps to reproduce:

Install Unifideck on a fresh SteamOS installation
Attempt Epic login via Unifideck — Edge opens, authentication completes but closes without handing credentials to Unifideck
Attempt Sync Library without logging in — existing Legendary credentials are not detected
Repeat on CachyOS — identical behaviour

Expected behaviour:

Epic auth completes via Edge and credentials are passed to Unifideck backend
OR existing Legendary credentials in ~/.config/legendary/ are detected automatically without requiring re-authentication through Edge

Actual behaviour:

Edge auth flow completes but closes without handing off
Legendary credentials not detected regardless of whether they exist on the system
GOG and Amazon auth windows also close without completing

Environment:

Tested on SteamOS (fresh install)
Tested on CachyOS
Same behaviour on both
Device: Lenovo Legion Go

[felipecpaiva]

Facing exactly the same problem on Steam is 3.9 Legion Go 2, Fresh install.