Unable to see Social Q&A questions. Can only see the questions when viewing the Questions related list on platform.

As per the doc here https://docs.servicenow.com/bundle/london-servicenow-platform/page/product/social-qanda/concept/c_SocialQAndASearch.html:
"Social Q&A uses the Contextual Search feature to generate search results."

You need to modify the active/applicable knowledge Search Context to now include Social Q&A.

1. Navigate to Search Contexts
   2. Click on the active/applicable knowledge search context (ex. Knowledge Base Search)
   3. Click the magnifying glass next to the Searcher field
   4. Select a searcher that contains 'Social Q&A' (ex. Knowledge, Social Q&A and pinned)
   5. Save the record