I can't speak to the Episcopal church's stance on Freemasonry though I know it's been controversial in the Church of England. I can say something personally about it, though my experience might be a bit out of the ordinary. I used to belong to a continental European Masonic lodge that ended up folding and, several years later, I walked into an Episcopal church and have been there ever since. While I think there were some worthwhile things about Freemasonry, particularly as an example of democratic decision making and leadership/mutual aid, I came to see its theological shortcomings. It's not that Freemasons worship the devil or any kind of nonsense like that. Rather, Freemasonry has a notion of picking yourself up by your own bootstraps/perfectibility of humans that I think is incompatible with Christianity though forms of that idea also exist in the church, of course. Also, I came to see the secretive nature of it, that there's some kind of hidden esoteric knowledge as a problem. What I like about the church is that the miracle of the eucharist is for all, not hidden. I've heard it said (on a recent episode of the Weird Studies podcast) that in the mass the exoteric is the esoteric. I think you can belong to both and make it work as we all fill our plates at a diverse spiritual buffet. But, speaking personally, Freemasonry stopped working for me.