I have found that if you fit the V1 upside down ie. With the nut on top it works fine. But the V2 is much betterThe thermowell I ordered came with a V1 bulkhead. It went on fine to start with, but there really isn't enough thread to get decent purchase on it (Kegland have since bought out a V2 with longer thread). My current brew was losing pressure through this and I couldn't tighten it up any further.
Big shout out to @BrewKegTap for sending me a new V2 version free of charge under warranty and incredibly quickly (arrived next day).