Trial of Chaos - Cannot Interact with Ritual Alter At All

Please help this is completely infuriating. I cannot interact with the alter in the second area of the trial of chaos at all. The one that starts a timer and summons waves.

It cannot be clicked on and shows no mouse over interaction. It simply cannot be activated, so I can't even complete the trial.

I have tried:

- Restarting the game
- Using a different key
- Starting a new instance

I've never had an issue with this on previous characters. I am currently continuing through Act 4 but need to complete this...

Thanks.