No, it never worked. Normally when you try to open something you get that Android dialog that asks you to choose an app. And I would assume it's supposed to work like that with the stuff from inside Google Drive since it's downloading them to the phone anyway, but it doesn't work like that. It tries to open it with the app, but doesn't.

Just wondering why you specified offline mode. That is definitely the third party app problem.

It sounds like an app problem then.