Custom POIs not refreshing in BaseCamp

OK, here's a weird one. Every week I upload speed camera files as POIs, so a .gpi file, to my nuvi. Recently a couple of cameras changed their speed limit, as the road speed limit had changed. My nuvi shows the new speeds as I approach the speed cameras.

BaseCamp however, using exactly the same file on my device, displays the old speed, so that data must be cached somewhere within the BaseCamp data/installation. I'm unable to find it so if anyone has any ideas that would be great!