[Plugin: Basic Google Maps Placemarks] Map showing *all* placemarkers, no filter

I’ve also tried changing the slug name to not start with a number, but it didn’t help

Does the same thing happen when you try other categories, or is it only that one? Can you try switching to the default theme, disabling all other plugins, and then check if it’s still happening?

Another user recently reported a similar problem when using the Post Types Order plugin. It is altering every query that WordPress runs, including those from BGMP, which messes things up.

It seems to work fine in regular posts, but not in my custom posts for products (using WP eCommerce) (the “products” are various tours around the country)…

Ah, ok. I’d guess that they’re modifying the queries in some way, but aren’t being careful and their modifications are affecting other queries as well. I’d try talking to them and seeing if they can check their code for that.