A side-effect of using SOLR to drive the collection display, causes non-display of collection description data:
Daniel Aitken conducted research into the issue, here are his findings:
"As for the overarching issue, it looks like the legacy SPARQL backend is being run through the 'islandora_basic_collection_wrapper' theme, which is what generates all that fancy metadata, and the newer backends are being run through the 'islandora_objects_subset' theme that gets manually wrapped in metadata - but the metadata wrapper doesn't have any alters for collection objects that mimic how metadata is built for the legacy SPARQL backend."
Furthermore, Daniel Aitken says:
"It sounds like an improvement task - something that brings the metadata display when using 'islandora_objects_subset' more in line with the metadata display when using 'islandora_basic_collection_wrapper'"