When our GL team was trying to close out the month, they were receiving the error "FRM-40654: Record has been updated. Requery block to see change." when trying to reverse a journal entry. After looking at everything we could regarding locks, and other people being in the record or the form, I finally researched on My Oracle Support to find the document "GLXJEENT: Journal Reversal gives Error FRM-40654: Record has been updated. Requery block to see change" via note 1135903.1 which helped me solve the problem.
There is an enhancement bug and it seems that even though it is marked as fixed in 188.8.131.52 we still encountered it on R12.1.3 so we need to find out what patch to apply to prevent this in the future!