About actual corruption I can't really help you with. (Very) Old blueprints can go corrupt badly.
There is indeed a new issue though, most blueprints (one from 0.15->0.18, not old) refuse to spawn in the latest release. You'll see an icon appear for a second and then it will disappear.
The logs tell you this: "Checking Empty: Core is not ok. Deleting object"
I do not know what is causing it but it will be fixed as soon as possible.
Oh and I don't know about SMEdit, it's a third party tool so we can't help you with that, the creator will have to check it himself.
[DOUBLEPOST=1418594158,1418590679][/DOUBLEPOST]Problem has been found, next dev (or release, maybe a new hotfix too?) should contain the fix.