I'll hope others may chime in on this one, but it looks to me as if you are doing the same thing that we refer to in language as a double negative, which negates the negative. In Word, if a Style already has Bold formatting and one then applies Bold to it, the Bold disappears.

In your case, I suspect that you would have to either have a clever macro to apply, or replace your hidden number formatting with another means of accomplishing the same end.

Best, Ulodesk