Line Spacing lost on compile to ebook

Hi all. Trying to compile a book into an ebook. I have three header styles and have set line spacing for these so that there is a gap before and after paragraph. Compiling ignores these settings and produces text with no gap before or after, even though I am compiling these sections as is. I have looked and looked and can find no way to make the resultant ebook leave space before or after the headings without having to put empty carriage returns in, which I understand is bad practice. Do I have to use blank lines to space before and after headers?