I'm having the same issue! Tried generating a new certificate 3 times already, and it always says the private key is not installed. It shows as OK in Keychain Access. Totally ridiculous situation, can't publish an important update for one of my apps.

Same here, I had 4 existing localizations that were green since a year ago. A week ago I added a 5th localization that for some unknown reason has stayed yellow, even after two approved app version updates. Even stranger that for one of my in-app-purchases, the new localization is green, but for the others yellow. I have done exactly the same things for all. IMHO, Apple doesn't seem to care much about giving developers useful (or even sensical) error messages, and haven't done so for decades.

Simply clicking "Allow" with an empty password worked for me. I do have a password set for the current user, but that one didn't work. As per usual, Apples user-messages make no sense at all.