So far there are very few details about the project, and reps for the actors and Carter have not confirmed whether or not the production was even underway (seems like an awful lot of effort for an indie drama, but who am I to judge?). Little is known about the story as well, but THR did say that it's "essentially a coming-of-age semiautobiographical character piece with no supernatural elements" -- well, you can't blame a guy for wanting to fight against type. Fencewalker was described as a "passion project" for Carter, who also wrote the script and independently financed the flick.
If you're familiar with Carter's M.O. when it comes to keeping secrets, then a covert project isn't exactly outside the realm of possibility. (Besides, if he's making a film about himself, why wouldn't he keep it secret -- he's a hush hush kind of guy!) Think about it, the man already managed to shock us once already this year -- what's one more surprise?