Any help would be greatly appreciated.
I can't see the rest of your feature tree but I am guessing that either your boss height is too low compared to your fin height or fin height is too high compared to your boss height, depending on which needs to be what.
In the example below if the boss height is 12, the boss will create ok but if I reduce the boss height down to 10 the preview of the boss goes red & when I try to confirm I get the same error message as you. You will need to play around with the boss height & fin height, when the settings are acceptable the boss colour will change back to grey.
Thank you for taking the time to respond and help!
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