When I assign an item to a sub-category in virtuemart, it shows up in the front end sometimes, but most of the time nothing shows up.

I tried deleting the alias of the categories and that worked at first. Then when I take the item off that category and save. Then put the item back on that category, it doesn't show up anymore.

When I try to assign the item to any other category it does not show up either.

Deleting the alias of the categories no longer works, the items just won't show up.

This only happens when I try to assign an item to a sub-category. If I assign them to top level categories they appear just fine.

Can you show me your site url, What's module that you're using to show your product ? i think you had selected display random product ?

Regards