I’m aware of ideas from Gary, David and Tevador. All of them seem to come with its own tradeoffs that are not small one of which I described here An open discussion on Non-interactive transactions - #80 by oryhp
It’s unfair to say they’ve been ignored. I and a few others have spent a lot of time thinking about them and discussing them publicly. The only complete solution I’ve seen is MingleJingle - though that’s an entirely different thing imo.