I received this message from a popular component developer in answer to a ticket regarding why i cannot load his module in SPPB by any method whatsoever. (Both J3.10.11 and 4.1.5 / SPPB 3.8.8.)
SPPB needs to be able to execute Content Plugins in order to allow you to use loadcontact or loadposition syntaxes. Please contact SPPB support to find out how it's done using their extension.
I was able to grok a solution by loading the component module into a custom module with 'prepare content' enabled into SPPB Joomla module, but this three-step seems inefficient and (for my clients, hopelessly) inefficient. Is this important facility going to be incorporated into a future version of SPPB? Can I add it to the wishlist?