Hi,
Ah, OK, I’ve got it now! It was a bug when using ‘center’. I found it and I’ll fix it in 2.38.4.
I think as a workaround you can use this syntax where you specify the lat/lng separately (also, in the beta you can just write ‘query’ instead of show and show_query). Here’s the shortcode:
[mashup width="100%" query="posts_per_page=25&category_name=members" directions="none" center_lat="-32" center_lng="122" marker_link="false"]
Please let me know if that doesn’t work for you, and thanks for reporting the problem.