I am using MarketPress with Headway theme. I've run into a problem with Pippin Williamson's Better Related Posts Widget (paid plug-in, available at CodeCanyon) that I can't resolve. I'm posting the details in the hope that someone can help.
Some background: I've been using Pippin Williamson's Posts by Taxonomy Widget Pro and Better Recent Posts Widget Pro (both also premium plug-ins) and both are working fine for me. Both recognize MarketPress's product custom post type and the associated taxonomies. Similarly, Better Related Posts works fine for me if I use it on a post page (and specify standard post type and post taxonomy, such as category), and it works fine for me with an FAQ widget (and specify the FAQ custom post type and associated FAQ taxonomy).
The problem is this: When I use Better Related Posts with a MarketPress product page and specify the product custom post type and the product_category taxonomy, it displays nothing. No matter what other choices I make in the widget, it displays nothing at all -- not even the title of the widget. (Other widgets in the same sidebar -- such as the shopping cart and Better Recent Posts, do display properly.) As with standard posts and FAQs, the widget clearly recognizes and allows me to select the proper post type (product) and the taxonomy (product_category). But nothing displays, even though I know there are products that should display.
So, summary so far: Pippin's Posts by Taxonomy Widget Pro and Better Recent Posts Widget Pro both work OK with MarketPress. Pippin's Better Related Posts works fine with standard posts and FAQ custom post types. But Better Related Posts does not function properly with MarketPress's products (even though it clearly recognizes and lists MarketPress's product post type and related taxonomies).
The one major difference between the first two plug-ins and Better Related Posts is that Better Related Posts needs to read the taxonomy of the custom post type (product, in this case) displayed on the page. I know that the taxonomies are there, because I can see them displayed at the bottom of the product (or post or FAQ) listing. But it appears that Better Related Posts cannot read the product taxonomy and thus displays nothing.
As noted, Better Related Posts has no problem reading the taxonomies of standard posts and FAQ custom post types. But it fails to read them, apparently, on product pages. Since it fails to read them only with MarketPress's products, I surmise that Better Related Posts is making the right queries but there's something different (non-standard?) about the way MarketPress's products indicate their taxonomies -- ie, product categories or product tags -- that prevents Better Related Posts from acquiring this information.
In discussing all this with Pippin, we agree on the possible/probable cause of the problem as described above, and he suggests (since I'm not a programer) that I ask this question: "Is there anything that the developers have done with the custom product taxonomies that would make it so that plugins have a hard time reading them?"
All software mentioned here is the most recent version. I'm working at the moment on a locally hosted test site, so I can't point to a page at the moment to "show" the problem. Not really sure how to "show" the problem (which is an empty space) anyway. I run the local host on a Mac running Lion, use Headway theme as mentioned above, and test on Chrome. For "official" tech support people, if you are out there, Pippin has given me permission to email you a copy of his Better Related Posts widget for testing and troubleshooting if that is of help. Any and all assistance in resolving this is greatly appreciated!