Sage 300 v2014

I have a situation where there is a gap in the I/C Adjustment Numbering and therefore can no longer drill down on their details from the I/C Adjustment Function. However, all postings to GL are correct and I/C Stock Transactions report shows correctly the details. Looking in the database, the header records in ICADEH are missing but all the child records in the Adjustment Posting Journal ICADJH/(D) tables are correct. I've run data integrity but nothing came up. 

I cannot figure out how this could have happened to prevent reoccurrence.  As far as I know an Adjustment cannot be deleted once it is posted. Has anyone encountered similar behavior or has any idea how this happened?