Ubisoft Connect 'login' button does nothing, blocking login with existing account.

Compatibility Report

• Name of the game with compatibility issues:
• Steam AppID of the game: Ubisoft Connect (all)

System Information

• GPU: Steamdeck APU
• Kernel version: SteamOS 3.4.4
• Proton version: 7.0.6, Proton Experimental (Feb 13 2023)

I confirm:

• [ x] that I haven't found an existing compatibility report for this game.
• [x ] that I have checked whether there are updates for my system available.

Will add logs later as I'm on my phone atm.

Symptoms

Logging in as an existing account holder on the Ubisoft Connect launcher fails as the "login" button does nothing. Tried tapping on the screen, pressing enter on the text fields, tabbing onto the button with the keyboard etc.

Reproduction

Open ubisoft game
When prompted, attempt to login with an existing account (NOT a new account!)
Click "log in"

Other notes

Notably, this is identical to the behaviour on Windows, however Ubisoft Connect support are instructing users to open the game/launcher in administrator mode which solves it.

I've done little research but apparently WINE already tells apps that they have admin privileges so this might be something unrelated?

PS sorry for lack of logs, not on my deck atm will add later if needed.

No source files, tests, or entry points are identified in the report. Reproduce the existing-account login flow on SteamOS with Proton and collect the missing logs; done requires a confirmed cause and a verified fix for the inactive login button.