When I merge two contacts I lose relationship info on both 4.6.5 and 4.7.3 The relationships come up as inactive with the current date as the end of the relationship. I don't see any errors except relationships are 0 after the merge and the relationships are shown as inactive
I did some research which points to a possible schema issue which suggests you verify the schema. I am somewhat concerned about doing that, especially where I need to merge 2 records, if it fails I either need to recover the database or find a new pair of records to merge.
I am looking at upgrading to 4.7.8 but not sure there are additional fixes which will resolve the issue.