Contextual Search does not return expected KB article
There are meta tags defined for Kb article that means when any one searches KB article using those meta tags should return the appropriate result. But sometime search doesn’t return the expected result
partial match rule defined as ‘-25%’ under text index for knowledge base table
After removing value for field ‘partial match rule’ resolves the issue
From performance point of view, OOTB partial match rule defined as ‘-25%’ that means whatever keywords you put will be detected by 25% and only platform search for 75% keywords configured for knowledge article. 75% of match could be random from the keywords selection.
Please check this below documentation URL to get more information about partial match rule