SQL plan baseline not used

Hello expert,

                     Recently we have upgraded our reporting database from 11.2.0.4 to 12.1.0.2 which is synced with production every night and opened in read-write mode.Before upgrading I have created sql tunning set consists of SQL query used by reports.After production database upgrade I imported that sts and created plan baseline out of that.As a result during sync it also came through in reporting database.Now interesting part is for one of the query plan baseline is not being used and that report is being executed for more than 30 mins instead of 5-7 mins average time in actual.I have no clue why