Please try this whole process:
- Revert to 1.3.2 via the Steam "Betas" option (or your platform equivalent)
- Launch the game and make sure that the affected account is logged in
- Click on the "Social Profile" button
- Set a username and click "Create Profile"
- Exit game
- Remove the 1.3.2 beta and get back to 2.x
- Account should now be able to access multiplayer
If that doesn't do it, Here’s what fixed this for two users:
- Uninstalled I:R and every folder on AppData and on Users/Documents/ relating to it.
- Did the same with every file related to Steam.
- Unbound PDX & Steam accounts.
- Deleted every entry on Windows registry related to Imperator.
- Erased the Temp folder on AppData.
- Restarted the pc.
- Linked Steam & PDX accounts.
- Downloaded Steam & I:R.
I hope that does it for you!