I think there is now an issue where when selecting the seal to show Scarlet you can't continue. It just grays out the choices once you pick and you can not exit the selection screen. I replayed to see if the issue persisted and on a new save I had the same issue.
Viewing post in Beta 1.6.9-3 and 1.6.9-4 changelog comments
Confirming this is an issue. Reverting to the previous version doesn't help, as that version has a bug where choosing a rune just does nothing at all. Had to go back to 1.6.8 to finally get past it.
If I had to guess, it's an issue with the developer swapping to a new method of choosing a rune (previously, instead of clicking on a symbol it just gave you a list of numbers to choose from). Likely when swapping to this new method, something went wrong when registering which rune was picked /acknowledging that a rune has been picked at all