If the style is set for 10 pts. after paragraphs, is it set to ignore space between paragraphs for paragraphs of the same style?
If not, then the style is not being applied uniformly, that is, some other style is being applied or direct formatting.
Paragraph spacing is not, generally, applied for a whole document but to each paragraph. A style applies it to all paragraphs to which the paragraph style applies.
Character Style v Paragraph Style v Linked Style