I often come across this type of grind when I do my talks on sharpening. It seems to stem from people watching Youtube clips but not understanding how a tool cuts, nor the importance of the tools cutting edge profile. It will be interesting to see some pics from Cornishchippy but I suspect the tool will look to have two horns protruding at the top of the flute. This happens if the tool is sharpened on a flat bed, and just rolled from side to side, without letting it move forward to grind the sides of the flute. Unfortunately the method of rolling the tool WILL work fine if you understand the profile you need, so it's not the method at fault, it's the end user.
Having said that, it's good to see that Cornishchippy has raised this BEFORE trying to use these tools. As others have said, I dread to think of the results if he had.