Some answers do not appear in search results

Summary

Some answers will not appear in search results, no matter what keywords you enter

Content

Some answers will not appear in search results, no matter what keywords you enter.  I have three answers which won't appear, even if I type the answer title in quotes.  I have tried adding keywords, confirmed that each answer has product and category assignment, linked products and categories, and checked keyword reports.  Interestingly, I have a second interface with similar content and those answers come up in search on that interface.  I double checked the PHP and widgets and for search, both interfaces are identical.  I doubt if it is a PHP issue because it works fine for most answers.