All my products are simple products. Check out the same link right now with WPSolr plugin disabled.
The pages that are empty probably have some posts with some data missing (book author for example) which are rendered as empty strings without WPSolr, but when WPSolr is active, they end up breaking the loop.
I’ll do some debugging at your get_posts override and see what is specific about this data and get back to you.