I don’t think it is an issue of updating the homepage, but BuddyPress uses the same query as search. So, as you pointed out, it might be because the homepage uses a query. I have no idea how to work around it though, aside from just using a different homepage, which has worked for me (no changes to search and filter, just changing my homepage). From the BuddyPress developers:
“If you have a Buddypress page set as the home page then blog search is killed because search sends you to /?s=xxx and then is searches the component instead of listing blog posts.”
Also, I think that the template that I was trying to use had a query because I placed the search and filter shortcode in the category and single page templates as well so that it could be activated from any page.