I haven't forgotten it just my real job has me very busy! The helpnote that explains about this topic is missing some information. It may be someplace else that I just missed. Not only can products be displayed on multiple sites using 1 database but also categories. So you could have one category displayed on one site but not the other or may be displayed on both. The problem is, at least with the "DisplayNavcategories", is that this function assumes that if xProductMatch is Yes (configuration table) then a category can ONLY be displayed on the site that is listed in xproductmatch field in shop$config.asp.
Looking at the function GenerateNavsql in shopnavcategories.asp the sql generated is:
SQL="Select * from categories "
sql = Sql & " where highercategoryid=" & highercategoryid
if getconfig("xproductmatch")="Yes" then
sql=sql & " and productmatch='" & xproductmatch & "'"
Which is SELECT * from categroies where highercategoryid = 0 AND productmatch='store1' ....
It probably should be SELECT * from categories where (highercategoryid = 0 and productmatch='store1') or (productmatch is null)...
Not sure if this is also what is cauing "NavigateShowCategoriesStyled", not to work correctly when xProductMatch = Yes.