I drove myself nutz today trying to get Caslon to V Carve a 6 as part of an address in a house sign. I finally figured out that it was rejecting Caslon. It wants to V Carve only the inner portion of the 6 (see the attached) I haven’t checked out too many other fonts, but they appear to be fine. I can’t be certain, but I don’t think this happened in earlier editions.
As a really short term fix could you invert a 9? the other option would be to create the shape in something like Inkskape and export it as an svg instead of lettering, should avoid confusion that way
The problem here is that some fonts aren’t put together properly, and don’t follow the rules of winding — the 6 has a clockwise path for the outermost path, and/or a counter-clockwise path for the counter, when it should have a counter-clockwise path for the outermost path, and a clockwise path for the counter.
You can fix this by using a version of Caslon which doesn’t have this technical error, or by converting to paths in an app which will allow you to correct the path directions.